I had unprotected sex with my boyfriend in August, but he pulled out. Ever since though, I've been really paranoid that I'm pregnant. Usually my periods are very regular, but since then I've had three periods at really random intervals (August 29, October 20, and November 9). The thing is, I usually bleed heavily, but all three of these periods were relatively light and brownish (they're usually red). I took a home pregnancy test on October 8th and it was negative. I'm starting to think that I've gained weight, but on the other hand I'm back at college and I always put on a little weight here. So my question is, am I being completely paranoid, or is there a chance that I'm pregnant?

It also might be helpful to know that I haven't seen him (and therefore had sex with him) since August because we live faraway from each other, and August was the first time that I'd seen him (and had sex) in many many months.

The chance that you're pregnant is relatively small. Test again or go see a doctor to ease your mind. Be careful so this doesn't happen again, I know it can be scary to wonder.