Do you see a gyno? Have they ever said anything about it? If it really is a problem then you should talk to a DR about it.
I sometimes feel a bit nervous in a swim suit because I think it is very noticeable. The first time I had a sexual act with someone, they commented on my large lips and I guess it's just stuck with me since then. The only interference I notice is when I go to the bathroom there is no seperation so I sometimes have to hold my lips open to avoid urine on my skin. My boyfriend doesn't really want me to do anything about it but says I should if it really bothers me that much.
How do you know they are unusually big? Did your boyfriend say so? Personally, I would not have surgery. Who sees it anyway? Is it interfering with your day to day living some how?