They tend to grow as you get older in general- when your period begins, most women do increase in breast size as well, but it's not an over-night thing. Takes a while. It all depends on the person because everyone is different. Some woman who are 25 don't have big breasts, and some who are 15 already have large ones so it depends.
I wish, I've already hit my period, and nothing...... *crickets outside* I think yeah that they grow as you get older.