Hello,
We must be about the same age. I'm still going thru puberty just like you. My breasts are still going to grow in the next 5 or 6 years if i'm lucky (I've read on the internet that breasts stop growing like 2 years after our first period, which is totally false, i've had my period at 10 years old and now, at (almost) 15 they're much bigger that they were when i was 12. Breasts stop growing when our body is fully grown, at 20 yo probably).
I'm a 36C, which was my mom's size when she was about 19 or 20, so I'll probably be bigger than her at that point of my life. It's true that our genes have a big weight on our size, but there are other things that influence it.
The thing that REALLY worked for me, and it's the only thing I'm doing right now, it's massaging my breasts when I wake up and before I go to bed, at night.
Here's the way I do it, and that worked for me: http://naturalremedysite.blogspot.pt/2007/11/increase-cup-size-in-30-days-with.html
I was about 94 cm when i started, and now i'm almost 98 cm. I started on May, so i think it's not bad at all since I'm only doing this massage.
Good luck, and don't give up. You'll need mental strenght to do this.
PS: There is another thing, that most women don't know. Men like all kind of breasts. The most beautiful and desired celebrities like Megan Fox (34C) or Angelina Jolie (36C) don't have HUGE breasts and yet men love them
This chart may come in handy: http://1.bp.blogspot.com/_tbn1HqJB8QY/TMf0uVozjjI/AAAAAAAAAkY/mLVY9huD_7o/s1600/bra+size+chart+2.jpg