You're not getting all of the slack out of the bar still. Hear how noisy it is when you start pulling?
Rock back off your toes first and make sure you're on midfoot.
Get all of the slack out of the bar. Keep lifting your chest and don't stop until you hear the plates "click" and your arms want to rip out of your shoulder joints.
Stay out over the bar as you press the ground away with your feet. Don't be in a rush to get behind the bar. Another way to think about this is imagine I have a hand on your upper back and a hand on your lower back and you have to push against both my hands with the same amount of force at the beginning.
You actually may benefit from deadlifting in flats or slippers with your build.