Hi I'm 20 years old and I normally have very regular cycles (28-32 days, never varies much outside that). I fooled around with my ex bf the last day of my period, which August 22nd, but we didn't have sex. I was supposed to get my period on the 16th of September. I have taken three pregnancy tests, all a week apart, including one yesterday, and they all came out negative. I did drop 11 pounds two weeks ago due to extreme stress. Haven't had much symptoms of anything, except my breasts will have sharp pains every now and then, some slight cramping and bloating buts that's it.  I have had major back pains though.