Plan B and late period

So I'm 19. My boyfriend and I were having sex last week and he said he might have cum in me a little. We were worried so we went out and got a plan B pill. I took it a little before 3 days after. I had zero side effects from the pill, which I thought was weird. I haven't had any emotional or physical pain lately, which sadly for me is rare. My period was suppose to start two days ago. Now I know I should not be worrying so early in the week but does plan B do something to your period schedule? I just need something to ease my mind right now. Or to just give me a heads up.