Thanks for the answer.
DL:
I find that I can't push with my quads when the bar is over the midfoot , I'd love to keep the bar closer but how can I "push the ground" when my hamstrings are so stretched ? I feel like I'm initiating the pull with only my hams/lower back and that it makes me too weak at the start: Here's a video of how I used to pull (about 2-3 years ago) https://www.youtube.com/watch?v=CduaUsijhJE
FS:
I'll try and keep my chest up. However , is the back angle low enough ? I mean , is the problem coming from my upper back dropping or from sitting back like in a back squat ?
Do you see any other issues related to my knees ?