OP says I already do those stretches
but thanks.
Today I preformed a body-weight PARALLEL squat. I was able to get down into the position and hold it, but I had to keep my arms extended out in front of me, placing them together in my hands to push out my knees would cause me to tip (as if it's impossible to do while keeping my back extended). It took me an hour of preparation to actually do this, and I wanted to giggle like a little school girl when I actually got it done. Fucking took forever.
I did it by literally forcing a squat holding onto something, keeping my back extended and just would hold it there for a minute or so, rest and repeat. About a half hour into it I started to let go of the pole and PUSH really hard on my heels while focusing hard on keeping my knees out, and eventually got to where I wouldn't tip over at parallel. Not sure how I'm going to break parallel, but yeah: progress.