@Shiloong
If I'm seeing it right, you're using your knees during the concentric phase instead of the hips. You'll need more hip drive. The hip drive is very important for the low bar squat as it helps to activate more lower back power, one reason why you can squat heavier with the low bar setup. Think of the hips as the prime mover here, probably that will help.
Also, again, your feet. Keep your heels planted firmly to the ground
at all times. Drive up using your heels as you get the most power out of it. If you notice, your heels tend to come up a little during the concentric phase. You don't want that as you will distribute more weight to the weaker muscles - the calves. This may also add to some instability during the movement.
Your wrists shouldn't be the major support of the bar. Try lowering the weight to 40-50kg and then work on your form first. Work on 'shelving' the bar properly and securely, and hold it with a thumbless grip. If you have sweaty palms, use some chalk. I had that exact problem with the wrists when I first started out. Switched to thumbless and that helped in alleviating the stress placed on the joints. It then took me some more time to get used to gripping thumbless. Your body will take time to adapt to the low bar setup, and along the way it will 'correct' certain issues by itself as the weight increases so it is important that you start off light to better your form first.
Form > poundage - anyday, anytime.
alright, gonna try and fix that the next session. thanks for the pointers. How often do you squat in a week ?