No Period yet and negative results?

Hi the first day of my last period was Mach the 16th. We are trying for baby #2, but no luck yet or IDK? I took another test this past Saturday and it came back ( - ) so IDK whats going on, one nigh I was really sick, and I'm tired ohh and headaches but I don't know what to do? I'm going to wait another week if I don't get it I'm going to a doctors office, so they can tell me whats wrong with me. I have never miss a period in my life till now. Can I be pregnant and the test are wrong? And I'm 26 y old.