Re: newbie user =)
Hi babyboonyc, there's no reason why you shouldn't do well with NB, although I know my daughter didn't start growing her boobs until she was 17 then they came from nowhere, she's now a full 32D, so you could still have some growing to do. Check out the stats page, I'm sure you will find young girls on there with a starting size similar to yours and you can read their progress. As for the cup size, if you have difficulty geting the medium cups on due to being petite you can always change to the small. Give it a go and see how you get on. Lucy will be very helpful if you have a problem.
Good luck!