I have the same problem with our OS Blueberry. I think that the MF/hemp insert that comes with it makes the nappy too large for DD. She's such a skinny minnie that the leg seals just aren't any good for her. There doesn't seem to be any gaping holes or anything, though, so it's a bit confusing. I think I'm going to start using the nappy with just an Easy Peasy hemp insert and a MF cloth, to try and reduce the bulk a bit and hope that works. Otherwise, it might have to go.
I really wanted to love this nappy, as it's so pretty and one that I wanted for a long time.