Sourdough Consistency

During your hand kneading keep a spray bottle handy to adjust for the tack. As to dense and heavy; it has more to do with the rising/proofing and shaping/handling.

Jim

Too much flour, use less, any sourdough that I've worked with is always tacky.  I like to use olive oil sometimes to create a non stick surface on my counter top/hands rather than adding more flour.

When you make a recipe, there is always some variation in how the dough will turn out. It can be because of a different brand of flour, a different season's flour having slightly less or more moisture, how compacted the flour was when measuring (measuring by weight helps with this),temp and humidity of the kitchen it is being made in,etc,etc. If the original recipe author describes the dough as "tacky but not sticky" and your is drier than that, either add a little less flour at the end or a little more water. This will just be the fine tuning that most recipes will need to have so it is important that the baker knows how to adapt to it.

The density is often a result of not rising or proofing it long enough. Let it go a little longer.

Sounds like the same issue I had. My initial doughs never felt quite like the recipe described. I eventually learned two things:

1. Measuring everything on the same digital scale by weight is critical. Just the "supposedly very small" errors of using a spring scale for flour and a different scale for water were enough to throw off the feel of the dough completely. I finally realized this was what was happening when I made exactly the "same" dough three times in a row and it felt different every time. (Measuring by volume can work  ...if you're so good at judging the feel of the dough that you automatically and correctly make small adjustments by adding a little more flour or a little more water. If you're not that good yet, then IMHO a digital scale is the only way to go.)
2. Different flours absorb slightly different amounts of water. A recipe that's "just right" for a particular brand of "All Purpose" flour will turn out a little too dry with "Bread" flour and need just a bit more water. I like the idea of using a spray bottle, as the needed additional amounts of water can be very small and as incorporating a little more water into a dough that's already come together is hard enough that spreading the water out all over the dough is a significant help. (If you try mixing in a bit of extra water right from the start, write down what you did so next time you can either do the exact same thing or do something different as appropriate.)