You need to take a pregnancy test. Although Plan B is highly effective, its not 100% and you could be pregnant. If your period was due March 5th and you are pregnant, you would be almost 5 weeks along already. I'm not sure how cycles work after taking it, but I definately wouldn't think you should be late for your period and cramps in early pregnancy are very common. So are sore breasts. Certain medications can interfere with Plan B just like certain medications can effect birth control, like antibiotics for example. Taking antibiotics while you're on birth control can cause birth control not to work. Are you on any birth control? If you're taking Plan B to avoid pregnancy, you should for surely be on some kind of birth control if you don't want to get pregnant. The only reason I can think of for Plan B making your period late is if it acts like birth control. When you start taking birth control, it can cause your cycles to go a little crazy at first until your body adjusts. The hormones in the Plan B could have messed with your cycle causing you to be a little late. Also..a lot of women experience cramps and sore breasts before their period comes. That may be why you're having that as well. You really do need to take a pregnancy test to be sure though. If its negative, then I'm sure your period is on its way and its just late due to being disrupted a bit.

so i took plan b and i was supposed to get my period on may 26th, i have no cramps, or signs of anything. what should i do?

Relax.

Did you have any bleeding or spotting after you took the pill?

If you missed, take a pregnancy test. But irregular periods is a very common side effect and you probably won't be getting your period at a normal time until 3 months after taking EC