Topic: Squat Form

[LMG462]

I am dusting the cobwebs off my joints and getting started in oly lifting again.  I am noticing when I squat (anything lower than 90 degrees) I can't keep my heels on the floor (with lifting shoes) and keep good posture.  I do a high bar back squat but as I descend to the bottom I lean forward and develop more of the angle of a power lifting squat even though the bar is high.  This happens barless as well.  I am fairly flexible however I feel that maybe a tight psoas and calves may be part of the problem.  Also, my core is extremely weak.  I am currently working on these weaknesses.  In the mean time should I only squat to the depth that I can keep good posture or go full depth with shoes that have a high chunky heal (I'm female) and allow me to keep good posture all the way to the bottom?  I was amazed to feel how activated my quads were when I was able to stay upright with the chunky heels.  Any thoughts?