I would try not to worry too much...and its hard.I know. I have gotten myself into a similiar situation and know the feeling is overwhelming. I had unprotected sex at the end of December when I believed I was nearing the start of my period...bad idea. I took emergency contraception and still haven't gotten my period, but I have taken 2 pregnancy tests, a week apart, and both have come back negative. I've done a lot of reading on it and stressful situations can delay or even prevent ovulation which would be a cause for you to be late. I'm hoping that is the case with my situation,b ut mostly because its not super unusual for me to be irregular. Sorry for all the background information but remember you are (we are) young and your body isn't totally on track yet, a late period shouldn't be super unusual. I would reccomend buying a pregnancy test and taking it, purely for your own peace of mind. I bought the clear blue one and it came with 2, I would reccomend getting something like that so if you test negative and are still worried a couple days later you can test again. keep your chin up and stay positive. hope some of this helped.