Hi there ..
Relax for a start... Depending on what sort of a cycle you have will all depend on when you get your period, most common is a 28 day cycle which means there is 28 days from the first day of your period to the first day of your next period. but it is also normal to have a 32 day cycle or 26 day cycle ... assuming you have a 28 day cycle and you are expecting your period on a certain date it is normal to sometimes get it a few days early or late.
If 1-2 weeks pass and there is still no period and you havnt been sexually active then perhaps a talk to your local doctor would be a good idea, there may be a problem etc that you may be unaware of, so a check up will never hurt.
So from what your explaining if you havnt received your period in the next week from today i would see a doctor but im sure you will :) best wishes :)