Pregnant??

I had sex on December 22nd. He was inside me for a little less than a minute without a condom. He said he didn't cum. Even when he put a condom on he still didn't cum inside me. I started birth control pills a few days before. I have now been on birth control for a month and I was supposed to get my period yesterday but i haven't gotten it yet. My periods normally aren't regular I just thought that after being on birth control they would be normal? Is there anyway I'm pregnant or is it normal for things to be a little off within the first month of starting birth control? I'm just really freaking out and need someone to talk to!