So, about 3 days before my period was due, I had a little bit of spotting after sex, since then I have had no signs of my period coming, and they're normally on time and regular, as I've been on the pill for a good couple of years, and it's now a week and a half since I should have started my period, so I did a couple of tests and they've all came back negative, anybody got any ideas what could have caused this? Or any advice? X