The most important think in your case is to be sure that you are not pregnant. If you didn't have sex you can't be pregnant. Period delay can be due to many reasons including stress.

My cycle always gets a little messed up around finals. I don't know if it's the stress or that I have a huge change from being at school then being at home--- probably a little bit of both

This last semester was the first time I've ever actually normal during/after finals was after I'd been on birth control for awhile. I'd consider it normal, as long as there's no chance of pregnancy.

I too had a problem with that once...I remember I had 5 big exams In ONE WEEK...i was up late for the entire week prior studying my butt off I was SO nervous and majorly stressed out, on top of that my long distance boyfriend and I were not doing well at the time which just put the cherry on top of everything, i had a stress overload and that month I was REALLY late..though, my periods were never on time, but i could usually guess when it would come...i think i was "supposed" to get it on the 18th or something and it didn't end up coming until the end of that month..it was ridiculous...

birth control is amazing..no more "late" or delayed periods