I agree with matias95 that you will need to learn to hip hinge. You can do this by placing most of your weight on your heels and pushing the hips back to generate tightness in the hips during the hinge movement.
Like I mentioned in my previous post, you can practice this by using RDLs to maintain upper body tightness while hinging and only using a ROM that allows you to keep a rigid torso. Your ROM and torso strength will increase over time to the point where you will feel strong in the start position when pulling from the floor. It might even be best to stick to only RDLs for a month or two instead of competition DLs to ingrain this technique and allow your mid back strength to catch up.