I wouldn't ever mention to anyone except someone really close to me, just because you never know how people take that sort of thing.
When I had lost 10 lbs and went back to the college I had transferred from to visit my old friends, one of the first things my old roommate said to me was "HAVE YOU LOST WEIGHT?!" But that's just the kind of person she is. Also, she hadn't seen me in about 6 months, so it was easier for her to notice. For people who see you every day and see the change so gradually, it might be harder to notice!!
But your weight loss is great!! And hey, if the bf notices, that can never hurt
