Sorry it took me so long to reply...thanks, holdingon. I had heard about women's cycles synchronising, it is very strange!

I guess I was under stress before because of the exams (should be used to those by now, though!), but they've finished now, and still no period. If it's not back by the end of the month, I'm going to try and get a doctor's appointment. I hope it is nothing, though. It's actually quite nice not having it!

Thanks.