Worried and scared ???

So AF didn't come last month (September) my last first day of my AF was August 1,2014 and I took a hpt and it was negative but I have been sneezing a lot gassy, nauseous sometimes but not enough to throw up, no appetite I only eat once a day, so what should I do I'm terrified what could it be. R these symptoms of pregnancy? ? I don't wanna give up its hard to track my AF and ovulation days