I am in some serious need of help!

I had my last period February 21st. I started spotting on March 22. The spotting lasted four days, until the 26th. A week and a half later still no period? I know it was spotting, or at least it wasn't a period. I wore tampons those four days because I was in class all day and I would rather be safe than sorry, and every time I took it out there was either NO or MINIMAL amounts of light brown stuff on it. Me and my boyfriend have never had unprotected sex, and I'm not on the pill or anything (yet.. I have a doctors appt to get BC on the 15th). So our only form of birth control as of right now is condoms. I took two HPT's and they were both negative about three days ago... any ideas on what this could be?