neverending period + the shot

[brionyy.livejournal.com]

I'm 17 and I didn't start my period until I was 14 but then I skipped a whole year and didn't have it until I was 15, and since then it's been only about 3 times a year. The doctors never seemed to find a problem with it since I'm young and still regulating and I'm also thin and fairly active. I lost my virginity a year ago and opted to take the shot in December. The first shot seemed effective and I didn't really bleed at all for the 3 months, but the second shot hasn't gone over so well. It worked for about a month then now I've basically had my period since the end of April, save for a few blood-free days. I decided not to get my third shot that was scheduled for early June but I still have not stopped the bleeding. It's not heavy but it's a really dark color now and just refuses to stop.

Okay sorry that was a long introduction but I guess these are my questions: I stopped having sex about 3 weeks before I started my period, so does the lack of sexual activity have anything to do with getting/maintaining it? and, Will this go away on its own or will I need to switch to a different form of birth control? My mother has breast cancer so I'm supposed to stay away from anything with a lot of hormones and I would prefer to just go off of birth control completely.

I'm scheduled to get a physical + pap smear within the next month or two but since it's summer I'm really hoping this can go fast and I would prefer not to get my doctor too involved. Thanks for any help anyone has to offer!