Bigger boobs?

Okay so I've been on birth control for about 3 months and I'm 19 and I just noticed that I feel like my boobs got bigger. But I'm 19 so I don't think that I'm going through puberty and they haven't grown in the past 2 months when I was on birth control. So I don't know what's going on. I had sex the day my period ended but a condom was used and I'm on birth control so I don't think I'm pregnant. Please help me