That's me, by the way. I may have been quiet on here of late (I've even been berated for it from some quarters!) but that doesn't mean I've been idle. As of a few minutes ago I've finished the most recent edit of Tiberius Found. Unlike a lot of other writers who find their word count drop significantly during the edit/re-write stage, I find that my word count goes up. The total count went from 75,000 to 77,000 - quite reasonable for the YA market, I think.
When I write the first draft I generally under-write and as I go through the iterations I tidy up the structure, remove redundant words/sections, correct any typos (and they always have a way of sneaking through) and expand any areas which need clarification. The up-shot of this process is a gain of 2,000 words from an original manuscript of 75,000. From what I understand, a lot of writers just get as much down during their first draft and then find themselves hacking and cutting the dross away to tighter up their story, but there are a few of us out there who seem to work the other way around.
I'm going to leave it for a while then do one more iteration - pretty much just as a read-through - to see what I think about it as a whole piece. Then it'll be put up on Amazon for Kindle.