Please help me. I'm desperate. ITS A GIRL QUESTION, BUT GUYS CAN ANSWER?

Now, this probably sounds like a really shallow question, but I am desperate. I'm 13 and have very small . All of my friends have waaaaaaaaaay bigger s than I do and the guys at my school including my guy friends tease me about my flatness. I am not completely flat, but none of the teasers will listen! I really need a pick me up or advice on what to tell them or tips on anything really. PLEASE HELP!