Weird Period And Pregnancy?

Okay, I got my period three days late (tuesday) and when I got it, it was just normal. That night I had unprotected sex, and then wednesday evening, my period just stopped. I had read that that could mean your pregnant, even though it's rare, so I thought I was pregnant, but then the morning after (thursday), it started up again, and it was like my normal period. That evening, it stopped again :s. (it's weird because it stopped very suddenly like I had never gotten it, then starts very suddenly) friday I had only a little bit of bleeding, suddenly starting that afternoon. It has been only a little bit on and off since then.
I have no idea what is going on! Could this mean i'm pregnant? How soon could I take a test? I had unprotected sex a couple days before my period too, could that have caused this? My period was normal (besides the random leaving) until friday, and not like the spotting I hear sometimes comes with pregnancy.
Any information is appreciated, thank you :)