What are some advantages of having small breasts?

I am the same cup size as you, if not AAA! :( I like that they do not get in the way when doing physical activity, such as running and other workouts. I am very active, so that is a plus. Like you, I do not like not having curves and not being able to fill out clothes nicely, but at the same time, some clothes do fit better because you do not have to worry about finding a bigger size or whatnot. Furthermore, since guys are so obsessed with big boobs, if you find a guy who does like you, you will not he likes you for much more than just your physique. I am sure you do have a beautiful body though, so be proud of what you have and know that you are gorgeous. :)