I'm 17. I've had my period for about 5 years or so now.
Last month I had two periods, 13 days apart.
34 days later I started again.
I'm on my 11th day, still haven't stopped. They usually last up to 6 days.
It hasn't been constant. At the very beginning, it wasn't heavy at all. It started getting heavy on the 6th day, and now since then it's been on and off. But, I bleed everyday. Sometimes, heavy, but I still discharge without bleeding through-out the day. I don't take birth control. I don't take any medication that would change my hormonal balance.
I'm sexually active. Would it have anything to do with having sex. Because when I thought I was off, my boyfriend and I had some complications with it. That's when I started bleeding the most.
Anyone have any ideas?

I'm not sure if it would have anything to do with being sexually active (unless you're pregnant; then almost anything is possible, it seems). It could honestly be nothing but stress but it could be very serious like Menorrhagia (excessive menstrual bleeding) or a pelvic inflammation. You should go and see your OB/GYN or if you don't have one, it's time to schedule a visit.

I used to have really infrequent periods followed by a week or two of heavy bleeding. It turned out to just be stress. I got on birth control (Otho Evra Patch) and it immediately started to regulate my periods. It'll also be double protection for both your period and your sexually active lifestyle.