Dropping your hips more as you set up would probably fix a fair portion of the issue. Also try not having that rolling start, at least not until you've fixed the back rounding. Set up with the bar so where between right on your shins and mid foot, with your shoulders behind the bar. Point your ribcage at the floor and push hard off the ground through your heels WITHOUT letting your hips shoot up too early.
Scrape the bar along your legs pulling it back into you more than up. Drop the weight down and just do lots of three to fives until you've got the new technique down.
For assistance I'd recommend a bunch of GHRs. Back extensions and goood mornings wouldn't hurt either, as well as heavy barbell rows with the torso fairly parallel to the ground.
Also, is there any particular reason you wear the belt so high? Where to out the belt is pretty personal so it isn't for me to tell you to lower it but I doubt it'd hurt to try with the belt a little lower.
I'd also recommend avoiding touch and go DL until you've got your technique sorted, simply because it will give you more time to make sure you're set just right for each rep if you go from a dead stop.