The first day of my last period was 19/10/16, I had unprotected sex on the 28/10/16 and 29/10/16. My period was due 19/11/16 but hasn't arrived. My period always comes on time but I'm 13 days late. Took 3 cheap pregnancy tests on the 2nd missed day, the 5th and the 10th but all negative. I've had more headaches than usual, feel bloated, peeing more and suffering more with my back. I've been feeling very nauseous when it comes to a night time to the point I'm vomiting on some occasions and also slight cramping. I've also had a tingling sensation in my boob but only one is kinda sore. Could I be pregnant?