Knluk It is very, very unikely that you are over-extracting, so don’t worry about it. You’re not measuring it anyway, so tell us how much you like/dislike, rather than second guessing unusual faults that you can’t diagnose.
It is much more likely that you are under-extracting.
Bitter happens for many reasons, not just one. Over-extraction is an intensely drying, smoke like bitterness, you’ll know when you get it. The result will not be drinkable.
You’re going round in circles if you go shorter, you’ll be grinding finer, making more bittering silt & the coffee will be so intense you won’t be making sense of it. Eventually you go too fine & extraction drops again.
Coffee is bitter, coffee is sour, it is often bitter & sour at the same time. It was roasted & is often charred/burnt…none of these things is helping us troubleshoot. Give us a numerical score, grind setting & ratio so we can see how they relate. Every bag of coffee tastes different but the dial in process is the same and the same things apply to all of them.
I’d go 1:3 and coarser until the coffee starts becoming too weak and tart/sharp, then tighten up the grind to where it tasted best. If you need more concentration, then look to shorten the ratio.
