I'm about a size 18 (post pregnancy) and a G cup, I didn't have any issues at all with the Moby wrap... And it is lovely and snuggly with a newborn.
I'm using a mei tai just now too and I love how quick it is to put on, but it isn't quite so kind on my back, though that could just be because I wear it for hours at a time! I think a Maya Tie might be kinder. Its like a mei tai but has wrap straps...