gahh.. confused..

I need help.. I had sex 2 days before my period started and have had cramping, nausea, breast tenderness, heartburn (I have never had heartburn in my life) for the past month, I have so many symptoms but my tests have been negative. I had my period for 2 days which was watery at the beginning, then heavy, then watery again. I know I should take another test, but what could be wrong with me if I’m not pregnant????