She never got a reduction, that's a weird persisting rumor. She went through some shit with a bad relationship and lost a lot of weight really quick over it. She mentioned it during one of her live streams back in the day. You could even see the shrinkage between pic sets, as well as the fact that there's zero scarring.
Not quite sure what her first topless vid was, but the first time she went topless was the underwater pool set, right around when she started doing the outfit changing behind that sheer curtain.