I found Isla needed to be in the lge peapods. I bought a med & it leaked heaps bad every single time.
After speaking with Alax from peapods all we could put it down to was her shape. Even though she is probably still in the weight range for mediums she has been in lge for over 12 months.
I had to add extra snaps to thelge to avoid wing drop & so I could cross over the wings.
She has a peapod on now actually & only just now have I not crossed over the wings. although around the waist is probably still a bit loose.