I'm not sure on my period dates, I'm pretty sure the first date of my last period was 6th of August, it's now 18th sept and I still haven't had a period, I can be irregular, but I've been having more headaches then usual, lower back pains like I'm about to have a period (but nothing happens) my breasts are quite sore. I akso get a metal test in my mouth quite freqyently in the day, I've taken 3 tests but have all came back negative. Am I pregnant?