Sourdough sandwich bread troubleshooting

Hi all,

This is my first post here, although I have been looking through the forum for some time. I have been trying to make this one recipe here: Simple Sourdough Toasting or Sandwich Bread | Alexandra's Kitchen (alexandracooks.com)

It is a sourdough sandwich bread, and it has good reviews and several others I know said it was their favourite recipe. But I just cannot get it to work. I have tried it several times now, and it has overproofed every time.

1. First time, fed my white bread flour sourdough starter the night before, and the morning of. 6 hours later it was bubbly and good, and it is a very well-established starter. I have made some very good bread with it over the summer. Followed the recipe, but lowered the water content slightly. So, I let it autolyse for 30 mins, then did four series of stretch and folds every 30 mins. I then let it rise for about 4 hours. It rose some, I shaped it as well as I could (it was very wet and difficult to do), and transferred to a loaf tin. Within an hour it was bubbly, but it never rose to the top of the pan, but it clearly overproofed so I had to bake it. It was okay, but the gluten mesh had broken down and there was very little oven spring.

2. Second time I tried it again but I reduced how much time it had on the counter. So I did the bulk ferment in the loaf tin in the fridge (about 14 hours I think) because it was rising a fair amount through the stretch and folds. Got more rise in the tin this time and the oven spring was better, but it still was just okay and it overproofed again.

3. This time, I decided to use my starter straight from the fridge (this is based on some experiments I have seen on YouTube from FoodGeek who found that you can do this, and have a longer fermentation time). I have had success with this before, because my starter is very strong and it means I can do a longer bulk ferment. I did three stretch and folds this time and popped it in the fridge overnight. I have been able to do this with other loaves. Again, overproofed.

4. I cut the starter amount in half the last time, unfed from the fridge. I did three stretch and folds after 30 mins of autolyse. And it overproofed so bad it was like soup. I turned it into focaccia which was very good but not what I wanted.

So I am unsure about this recipe. Too many stretch and folds? Should I try and even lower amount of starter? I have an incredibly small kitchen (like...it's basically a box, very very small). I have no straight sided containers to bulk ferment dough in because I just don't have the storage space for something like that, I don't have a thermometer or thermostat, as I live in Ireland and it's humid and generally feels cold, but there is no proper temperature regulation, I just have to turn the radiators on and off to keep the place warm. So it's hard to control the temperature, but right now it is colder in my flat. But I find it strange that my sourdoughs over the summer when it was hot were so much more successful than now, when they are overfermenting on the counter.