Possible pregnancy?!

[https://users.livejournal.com/-beautyispain-/]

I have a really, really weird question. I went to the beach, and right when I got back I got my period. Lasted for the usual week, then it stopped and soon after (a couple days) I went over to spend the night at my boyfriends house and we had sex. We used protection, but I'm not on the pill. The night after I had a heavy night of drinking, then the next day, I had my period again. But it started out as the real (sorry this is gross :/) rusty color your blood turns when your period is coming to an end, and got heavy like a usual period (still rusty), then ended with normal blood red colored, light spotting. Now, 2 weeks later, I'm having minimal spotting again with the rusty color. What the HECK is going on?! Should I be worried, like as in pregnancy? I can't think it to be possible especially after the drinking and 'period' but it wasn't normal colored so I don't know what to think.