I think the biggest thing holding you back at the moment is that you're coming up on your toes early:
and that position is subsequently affecting your power.
Try keeping the weight on your heels a bit longer leading into the 2nd pull. See Steiner's sequence and notice how late into the lift he keeps his feet planted:
Also, get your back set tight (arched) before you commence the lift. You get a bit of air time, but I wouldn't lose sleep over that right now.