I was two weeks late on my period. I immediately became paranoid that it was because i was pregnant. i've only had sex 4 times...all four were protected. I took a pregnancy test a month later...negative...waited a week....negative. So i went about my business. I finally got my period but now i've had it for almost 3 weeks. the first two being spot bleeding and this past week the flow of blood has been very heavy and seemingly constant. Is this just my body regulating as i mature through the teenage years...or should i really see a doctor???