Pregnancy????

So I have never been pregnant before and slightly panicking. About the middle of last month my bf and I had unprotected sex and it was one of my safer days so he came inside..... now I'm wondering if I'm pregnant because my period was suppose to start 6 days ago.... I have been nauseous and super hungry and real tired as of late. But the thing is I took 3 pregnancy tests and each one was negative. I work nights and right now I'm in the process of a new job just waiting back to get through all the yellow tape. So my stress level is high. I'm not sure if I'm pregnant or stressed out. I don't have a doctor because my health insurance sucks and I'm getting better insurance with my new job. For all the women on here who have more experience in this area PLEASE HELP I have no clue what to do and my new job isn't one where I can be pregnant right from the start. So I'm freaking out here