C.S.
As I believe this is a total personal decision, but since you asked I am happy to share what I think. I personally wouldn't do anything permanent. You are still young. Life changes us a lot and who knows in ten years you man be with someone wonderful and the two of you may want to have a child together. Just last night I was with a friend that at 22 had her tubes tied because she was not going to have any more children with her then husband. She now is in a really loving relationship, only 30 and really wishes she could have another baby. With that said, if you are happy with the IUD why not stay with it?