There is a type of surgery called labia reduction.

Personally I would not have any kind of surgery done unless it was a matter of life and death...and I may not have it done then !

Good luck. If you want to check out http://www.google.com just type the key words into the search box.

Blueduck

You don't say how old you are, which may be relevant -- as estrogen levels decrease approaching menopause it's normal to experience some changes to the labia. Some women find the outer labia more or less disappear -- the fat disappears from them and they atrophy so that the areas which were formerly covered are no longer protected. Other women find that as estrogen levels drop the labia have a tendency to close up and fuse together. Everyone's different. I think the best answer is not to worry about it. In any case, it shouldn't stop you wearing a swimsuit -- just make sure the crotch is lined.