Just as many women have smaller breasts as women who have larger ones. The average breast size is, not surprisingly, pretty darn average. And amazingly enough, women with breasts of all size can love them (remember too, your breasts, like your hands, aren't merely decorative -- they're crucial body parts that serve an important function regardless of size, not a pair of earrings, love). Your mother's breast size may or may not have anything to do with yours. I know I grew up feeling a bit like a freakaziod because I was the only woman in my mothers' family with larger breasts, while they all had small ones. Thankfully, I got over that feeling pretty easily.
Might your breasts grow more? They might, but at your age, if you started purberty before or at the start of your teens, they likely won't grow much more, no. And there are no "signs."
Which is likely for the best: your energy is best spent learning to like and accept your body as is then looking for signs it'll change.
So hey, pick a bathing suit you like you'll have fun in and feel great in, and start thinking about your body on different terms: as-is can be as great as might-be, and all the better because you've already got it!
Editor and Founder, Scarleteen
My epitaph should read: "She worked herself into this ground."
-- Kay Bailey Hutchinson