should I be worried

me and my bf were having sex, without a condom. according to my period and stuff, it wasn't during my fertile time, however he pulled out at the last mintue and it's possible a little got in me.  I took the plan b pill 45 minutes after but I'm a super worry wart and this is really stressing me out. this happened 4 days ago and I'm supposed to get my period in 5 days. will plan b make it late? is it even possible I'm pregnant? I feel like it isn't but like I said I'm SUCH a worry wart.