Could you give us a little more info to go by?
Like how old are you? Are you on any kind of birth control? Was your last period normal? How many days are in your cycle? Is your cycle normally regular?

No im not on any birth control and im 17 years old

And yes my period is normal eveytime and and my cycle # is ever 28 days

Usually when you are stressed out or in the months with 31 days your peroid may come late..Nothing to worry about..Try to relax..

Yeah if that rule applied how would your body cope in february? Especially on a leap year.. Crap!

You should go to your doctor and see if he can give you something to help you start your period. Yes, they do that.

It can be quite normal for some people to completely skip a month now and again. Our cycles change throughout our lives and what is normal one month, isn't always normal for several months. Like the amount of days between periods, or the amount of days you bleed, the amount of cramping, etc. All of those are variables.

Since it has been over a month since you had a period, you should see your doctor. Especially since pregnancy has been ruled out.

Hold on guys I am not saying that she could not be pregnant, but doctors usually say that women who are between the ages of 13-17 periods usually change from adolence to woman hood. From 18-21 you body will change again, and from 21-30..So with that being said your period will change because of age..