Lots of symptoms and no period yet...but negative tests...

So I had unprotected sex the beginning of October. The first day of my last period was September 20th. I have been having symptoms like I still haven't had my period, my breasts are sensitive, I'm experiencing fatigue, occasional spurts of nausea(no vomiting though), my lower back hurts, I get headaches more often than usual, I have this weird white/clear stuff that comes out of my vagina sometimes, I've gained some weight, my moods are all over the place...but the thing is I have taken three at home tests that all came up negative and a blood test at the doctor and that came up negative too. I'm still getting symptoms though...could I be pregnant? I have this feeling I am, but I have had that feeling before and turned out not to be but I didn't have symptoms then like I do now? Anyone have some advice? I'm so confused...