I hear ya about not necessarily liking to be on a first-name basis with vet
, but I think it this case, you might need to go back. If the gap penetrates deep enough to be anywhere near the bone and it gets infected, London would be in a world of trouble. She might need a stitch, too, if it gapes every time she sits down.
Go easy on the peroxide now that it's been cleaned thoroughly--peroxide attacks healthy tissue and can impede healing. The vet can tell you the best way to keep it clean once it's been evaluated.
. It's the best advice I can give you.