My last period began August 26th and I am always regular. I had sex on the 8th,11th, and 12th September (which I now know to be my ovulation days. My period has arrived 9 days early (if I've calculated it right) and I woke up with immense cramps and a light pinkish period. My periods are normally heavy and I have back pain but I have had none of this. It is has been so light and pink. Should I take a pregnancy test? I know that a certain named brand can detect early but will it still detect if I am bleeding? I really do need sensible advice.