First, you're throwing with the wrong hand! (Sorry, that joke never gets old for me.)
Second, you definitely need to get your weight forward more. You shoudn't have any weight on your back foot when you get into the power zone (when the disc passes your left pec.) I'd work on that before messing with anything else. That Dan Beto video where he works from the hit back will help with that a lot. Try shortning up your plant step to see if that makes it easier, too. It will probably mess up your throw for a little while, but if you can do all the same stuff you're doing now but with your weight forward I think you'll be pretty happy with the results.
Thrid, and this is for everyone else, watch how slow he comes into the power zone and how late he accelerates.