Your boobs could be perfectly normal size. The thing is in modern times many people are used to images of girls with huge boobs, so basically our preception of boobs is far too great. I wouldn't stress it really.
I love how large breasted chicks sit there and say, "Ugh! I hate my big boobs!" and then wear low cut shirts and shove them in everyone's face. Smaller breasts are tasteful, and allow you to develop a *gasp!* PERSONALITY.