Sounds like you're over-thinking this a little.
Here's the problem you have to solve with your body: stay balanced on midfoot through the entire ROM
Here are your constraints: bar under the spine of the scaps, hip crease below the top of the patella in the bottom.
There's obviously more to it, but start with that.
If you're taking the correct stance, the knees shouldn't go straight forward, but should track in line with the feet.
The bar path may not be straight and/or you're not driving the hips up out of the bottom.
Read the sticky on posting videos and post one up.