pms + sleep deprivation? or pregnant?

Hey, I'm 18, first semester college freshman and recently had sex for the first time (sept 26th), but we didn't have a condom so my boyfriend pulled out before he came. My periods are very heavy and irregular (sometimes a 25 day, 28 day or 34 day cycle) and right now I'm experiencing some light spotting, which I'm not sure if it's the start of my period. My last period was sept. 7th and that was the 34th day of my cycle. I'm in a really intense drawing class this semester and pulled a double all-nighter from the 29th to the 2nd and on the 1st started experiencing headaches, breast tenderness and cramps, and on the 2nd I started getting really nauseous and bloated. At this point I'd only had 3 hours of sleep in 48 hours. I'm not sure if I should chalk these symptoms up to pms and a lack of sleep, or possible pregnancy...help!