When we did use pockets, I always found the side snap WN to be fab - excellent fit and really pretty. The one size popper pockets we struggled more with. DD is quite skinny and I used to get leg gape with the OS for some reason. The fit of OS pockets was much better when they were aplix fastening. Except DD can undo aplix, so that wasn't ideal.
I'd try a preloved pocket to see about fit, then splash out on something new once you know they work for your LO.