Question about exercise?

So I'm looking to lose about 15-20 lbs and get back down to the weight I use to be (130.) But, how much will my boobs "shrink"? lol I'm a B ...just about a C, right now. If I lose 20 lbs, how much will it affect the girls? Just curious :) Not all too concerned with it. If they get smaller, oh well...at least I will have a kick *** body thanks to the Insanity workouts!! :)