Under-proof and over-proof

The starter was created January 20th this year. 
so not exactly a 10years mature starter. But definitely able to create decent enough bread as iv used it for other bread recipes, but as it’s still relatively young I’m not expecting miracles,  though for the most part it does work just maybe not so well as it could as it’s not developed to that stage yet. 
it’s 100% hydration starter.

40g starter 100 flour 100 water

usually done with bread flour, but iv gone on to wholemeal for now as iv heard it’s better for making a more active starter.

the one on the right (the flatter one) was baked first, and came out a bit gummy and a bit dense.

Then about an hour later, the other went in (the one with the air pocket), and came out lighter and nearly gummy at all.

Both baked direct from the fridge.

what I use to bake it in is a old flat handle less non stick pan, and a saucepan which I use as a lid to create the steam effect that you’d otherwise get from using a Dutch oven; obviously I don't have one of these yet, given the current situation with being furloughed at the moment, I’m sure you can understand not wanting to spend money on something, when I can use something else to simulate the same effect.

so that goes in the oven; fan assisted and heated from the back, at 270c for 10 mins to preheat the oven, then I set a  30 mins timer to get it proper hot, with my mock Dutch oven inside.

As soon as the loaf goes in , I turn it down to 230c and bake for 30. Then remove the lid and bake out for another 15 mins, which then gives an internal temperature of near 210f.

both loaves have unfortunately gone now lol. It’s taste really good every time, but it’s always something different that’s gone wrong with its.

I just find it hard to imagine that if both were at the same stage of development, how they come out that different. I’d of thought they would either be both under or over proofed. Surely I’m not over-proofing In the time I’m baking the first one ?

both bottom crusts had been about as dark and as thick as the rest of it; to mean,No more or less than the the rest of the loaf, it was not a very thick crust, if that helps?

you mentioned a Levian issue from what you can assume from what iv mentioned and from looking at the crumb..... is this a reference to how flat the loaf is in general?

My loaves have generally been a bit flatter than I’d of liked, so I would wonder if, as you asked about the age of the starter at the beginning... maybe it’s that it’s not mature enough or even active enough in the first place? Would using whole grain in my starter help this? Looking at my starter now, it’s risen higher than the original bread flour I was using. So I would take this as a good sign.
Maybe as a test I could try doing the recipe again but with a wholemeal starter instead ? Or would you suggest it could be still a bit to early for that?

sorry iv created an essay ? . I’m just a bit eager as you’ve probably worked out. Il consider what you’ve advised so far when I do my next bake. And I look forward to what you can further advise me with, with the feedback given.

One was on the bottom shelf and the other was on the shelf above.

In all honesty this wasn’t something I’d of thought to consider. The fridge was a consistent temp of between 2c/4c for the approximate 15 hrs it was In the fridge for.

without thinking this would be a issue, I hadn’t thought to check the positioning of them both in the fridge. But I am aware that the top shelf is usually a touch warmer in most fridges- my own included. So I avoid proofing anything on that shelf anyway.

without thinking fridge positioning would be a issue, I then didn’t think to point this out - even to myself.

but I do know the fridge temp was consistent as I had  a glass of juice I was taking a reading from, and I did ever so gently touch the side of the loaves a few times with the temperature stick just to make sure nothing had changed significantly.

It hadn’t. 
they stayed both the same.

if I had to guess, I’d say the over proofed one was on the higher shelf but as I was taking readings with a probe, (which both came out as the same temp) I didn’t expect either to be that different when baked.

Sorry I’m still very uneducated with technical terms. When you say too acidic  , do you mean it’s to young/not mature enough? How do you know if it’s ready?

I feed once every morning at about 9 or 10 and leave at room temp-about 68f/70f . And that’s it, I don’t stir as it seemed active enough without the agitation as it was doubling in size in about 9/10hrs though it slowly started to stop doubling after a while. If I’m baking with it,I mix however much the recipe asks for the night before to create the levian and leave it at room temperature next to the mother starter and check it the following morning by it passing the float test before using.  
but otherwise the remaining starter which has continued to do its thing undisturbed overnight is then fed as per its usual cycle. The discard I keep in the fridge and make crumpets or pancakes with once a week; but that’s a different story lol?

as to the birth of the starter...... January 20th.
To be fair I have swapped the flours about a bit, to begin with I used British plain flour 9.1 protein to get it started, which didn’t seem to do a lot, so went on to a local wholemeal flour 13.2protein  for about 2 weeks until it was real active and I got a reasonable loaf from it, I then changed to a local bread flour brand 13.3 both flours are the same brand (marriages)  and are both my preferred choice as they are relatively local to me, that’s the story of the starter thus far.

Except, i have today gone back to the wholemeal as I have heard that whole grains are better for starters as they have more nutrition..... or something like that. And it has doubled for the first time in a couple of weeks today as a result. And given that a few times it’s been mentioned that it could in part be due to the inactivity of the starter I felt this was probably the right move in this particular area.

both these flours are used as part of the loaf recipe as well and not just for the starter. 
the recipe in question, yes does indeed say all purpose flour which I had taken to mean British plain to begin with.  
But not believing that British plain and u.s all purpose are exactly the same (having checked the protein content) I did a plain flour loaf and a bread flour loaf to see if there was a difference. 
of course there was a difference, the bread flour loaf came out superior to the plain.
naturally I’m not going to import a flour specific to the recipe from halfway around the world just to make a loaf of bread from time to time, but I had considered maybe mixing some of the plain flour and bread flour I have available to get the protein balance to match that  of the King Arthur flour which I believe is 11.7? I haven’t got that far yet in trialling this theory, but its on my list of trial loaves to try.
Would this work or is that not how it works?
The protein content I believe for the King Arthur flour is only 1.3 less than my available bread flour so didn’t  think it would have a massive impact. Is this not the case? Would that little make that much difference?

I kind of figured out that the plain flour I used in the first loaf lacked the protein and gluten in it to bake a good loaf. Plain flour for me here is usually for making cakes with and generally not flour for bread baking. But always the optimist I tried it out just in case, -it failed lol. 
if it helps to further understand what I’m doing, the recipe is the Vermont sourdough from the King Arthur baking site. I watched the video to see what it should be like, and followed his method of doing the folds for 10 mins every 50 mins and repeat. (Or so I gathered)
though when I done this the first time with the plain flour with a lower protein content of  9.1 as apposed to the bread flour it was easier to do the folding due to the lack of gluten available in the flour. And the dough in the video looked equally easy enough to fold as well, so I felt I was on The right track doing it this way.
Something I noted. was with how easy the dough looked to work with in the video and the ease at which I was then doing it myself. I felt this would work. But alas it failed utterly.
the bread flour though which has a higher protein content 13.3 in contrast was much harder to work with, it was resistant  to more than a couple of folds each time I had a go at it. And with not wanting to risk tearing it and losing any gases, I only did a few folds as apposed  to a full 10 mins of folding. Something that the gent in The video didn't seem to struggle with at all. this was no doubt due to the difference in the flours we used and the extra gluten In the bread flour I was then using.  -again, so iv gathered.
Which first led me to think that I should maybe mix a blend of the two flours to get a healthy protein content that matches the one in the recipe and with enough gluten in it to help provide the strength, which with plain flour alone wouldn’t do, but still give  me enough looseness to the dough to do that much folding?
but from what it sounds like, and from what I’m starting  to understand, is that before we get to that stage.... it is more likely to be a starter issue?
As any loaf I make, regardless of the flour used and whether it’s under or over proofed it comes out relatively the same. I’m understanding the characteristics of the differences once iv bake them, but not yet learnt to notice them beforehand. 
Apart from the giant bubble from a over proofed loaf and the gummyness of a under proofed one they are all coming out relatively the same -flat. 
is this ultimately down to a weak starter? Would using wholegrain flour  as a starter base resolve this, due to the extra nutrition available?  And would fixing this give me bread with more lift? And if so how much more lift  would it give? I dont expect a Miracle cure that’ll give perfect baked bread every time, iv still a fair way to go before then, but would this massively help with the end loaf?
if going by the Current picture as a reference, if I got this right, would it, say double in volume?  And if I take all of that into account, do I still need to allow for time as well to help it develop? Or would just a few wholegrain feeds get me there? I’d always thought the float test was ‘the test’ that said it was good enough to use. But if that’s not the case, then how do you know when it’s ready? Or have I missed something?

and to answer the Dutch oven question. Yes both go In at the same time for that amount of time for 40mins with the lid covering the top to trap steam prior to the the bake.

sorry for the essay of a response, I swear the more answers I read, the more questions I then feel I need to ask. I could probably write a book of questions by the end of this ?