Wow are those 45's, you are so tall you make them look like 25's.
I thought I was tall (6'2")...how tall are you?
Anyway, the biggest problem is your back doesn't get "set". It looks round most of the time. The belt position may be such that it is screwing with your ability to extend your entire spine...or it may be that you don't know what it feels like. Anyhow, you have to "set" your back much better.
Finally, the bar is not over your midfoot and thusly your hips are too low for you anthropometry. This is causing your hips to go up first without any movement of the load. So bring the bar in closer, about an inch from your shins.