Hehe! I think this is one of those how long is a piece of string things and we just have to learn to be patient! Shouldn't be too long if you've already been through several rounds of revisions (it can be held up of one reviewer says they are now too busy and so it has to be reassigned to someone else... or it can be held up just if one party, ie a reviewer or the editor, is slow for whatever reason). Fingers crossed!