While on birth control pill, is a secondary line of protection that important?

I have been ually active for about four years now and I have been on birth control the entire time. I have never used a condom or any other method of protection, and have never gotten pregnant. (I have been with one man this whole time so STDs aren't a concern) But I do wonder sometimes, am I just lucky? I never ever ever want yo have children, and I do plan on getting married. Is the pill going to be enough for the rest of my life? Should I consider any other methods? I would love for my fiancee to get a vasectomy, but I would never want to ask that of him, even though getting my tubes tied would be much more difficult.