I don't mean to scare you (sorry!). I just, from the pic, it looked pretty obvious that one is rather larger than the other. Keep in mind, we've all got some sort of unevenness. I don't think anyone's perfectly symmetrical unless they've got nothing up there or they've had surgery. It was just, to me, it was noticeable, so that should be a red flag.
Just get it checked. I am no doctor. I'd rather you knew it was a false alarm, than that you didn't know, and something happened, okay?