My DD2 is skinny, but what weight she has is all in the thighs & butt. I've had good luck with one-size diaps like BG and goodmamas. Imse Vimse fit really well, we only use IV wraps and have one AIO with snaps and it's great.
I hate to say it because velcro/aplix is so annoying but you can get a much better fit with it when you have disproportionate thighs and waist. We have mostly BGOS and one BG AIO with snaps, and the BGOS are so much easier to get on (but the AIO is soooo nice.)
Goodmamas are awesome but bulky and pricey--they're having a sale right now so I just splurged because they fit my LO so well and my 3yo uses them for night dipes too. I also like the various dipes without fastenings like tots bots, bsrb etc, they are nice and customizable.
HTH!