So for the past half year, I think I have taken 3 or 4 Plan B pills and I remember I got a late one in January/ February. I was ignorant of the side effects of the pill and thank goodness I've learned (still learning) what it does and didn't take one again until last month because we got frisky (but still got my period and yes we do use condoms after this). Now I am 4 days late of my period and now I'm asking, did the effect affect me just this month then? I took a test, I'm not pregnant and going to try again next week just in case.