Brown clot like periods

For several months I have noticed that my periods are very light, not heavy enough to use a tampon. They are also very dark brown and I seem to discharge things that look like gel-like blood clots maybe. These periods don't last as long as my normal period did. I have been on birth control for 2 years now. When I was younger before I was sexually active I would have very abnormal heavy painful periods. I once went a stretch of 8 months without having one. Now, they are very light and last only a few days. I also have some pain during intercourse. I have had ultrasounds done and they had said that everything is fine. Anyone have any clue as to what is going on with me?