It's very very common. I've read a lot of posts on message boards from women asking the same thing. There's nothing you can do to change it other than expensive surgery when you're an adult and have thousands of dollars to throw around, but I think it would be a waste of money. Our bodies aren't supposed to be perfectly symmetrical. Don't worry that your boyfriend minds; I'm sure it doesn't faze him. You could always ask him; I'll bet he says he didn't even notice.
There's a book called "Femalia." It's a little picture book of many different women's private parts, so you can see just how normal you are!!