Possibly pregnant, yuck, help please?

So about 2 months ago I had missed a pill, the next day I took the missed pill and the regular pill and had unprotected sex the same day. He didn't come all the way inside me. About 2 weeks later I had my period but it was lighter and only lasted 5 days. Now (a month later) I'm waiting for my period and it still hasn't come its 3 days late but I've always been irregular and I've been stressed out lately. Could it be that I am pregnant? advice please. thanks :)