I don't know if i'm pregnant please help

I had unprotected sex over thanks giving and used the plan b pill and that messes your cycle up, i'm somewhat consistent and got my period right after taking the pill which was only 2 weeks after my last period. I didn't have sex again until this week and I had sex a few times but every time he pulled out and finished on his own. I haven't gotten my period since that time after plan b and I'm 6 days late, it's only been a month but typically i get mine every 21 days. I don't know what to do... thoughts?? what should I do?? I'm scared