Firstly, I wish I could squat 310 for reps when I was 17. I wish I knew what a squat was when I was 17. However, I digress. I don't notice your knees caving in too much, at least not from this angle. I do see you dropping into the bottom of the squat, getting a little loose and then kicking your butt back instead of up. You then follow this by lifting your chest mid way through the movement. Descend a little more slowly. Don't go four inches below parallel. Drive your ass straight up and continue to push with the hips all the way to the top of the movement. Nice work.