Why is this happening and is this normal?

IAs of right now, I am 17 1/2. A little more than a year ago, I wore an A/B cup bra. I acutally weigh a little LESS than I did last year, and now I am spilling out of most 32D cup bras, and just bought a 32DD bra! Also, the are starting to look a little more defined, i guess. The wierd thing is, I stopped growing in height at age 13.5, and I started getting my period at EXACTLY 12.5 (but my periods did not become regular until last year! lol). I LOVE this... but I actually see men and guys staring at my etts. I say that I am "fat," but I am not chubby in any way (except for my backside!) A few months ago, I went to buy a new bra, and the saleslady told me that when she was 16 y/o she was an A cup, and a year later she was a DDD cup! Is this story probably true or made up? Also, since I have gotten my period a LONG time ago, and have stopped growing in height and have not gained weight (knock on wood), why are my etts still growing? Is this normal?