Plan B. Help!

I had just finished my period on Jan. 2nd and I had unprotected sex Jan. 6th. He pulled out but I was still really scared so I took Plan B and a week later I got my period again on Jan 11th! I thought it must've just been a side effect of the pill and the instructions tell you that even if you bleed you should expect your period when it's due. Well my period was due yesterday the 25th and I haven't started! I am freaking out.. Do y'all think I could be pregnant or the pill just messed my cycle up?