for those 10 days your form has gotten better, but I want to point something out
the point with sumo deadlifting is to use the barbell to pull yourself into position
I don't approve that rolling thing you do like a strongman (Bennie does it, Brian Shaw does it, I think Eddie Hall does it as well. But they pull conventionalish)
Also, don't try to have an explosive start. Sumo pulling tends to be slow at the beggining and more powerful at lockout.