Advice please!! Scared!!!

OK so officially today my period is a week and 2 days late. Had unprotected sex bout 3-4 weeks ago now I suppose. Not TTC! I'm freaking out. At work last night I was standing there and threw up out of no where. I pee all the time, but I drink a lot of fluids. Everything is making me sick. I've taken 3 tests and all were negative. Am I stressing myself into symptoms or could I have a good chance of being pregnant? I'm on the pill and have no way to get a blood test done or go see a doctor.