What’s wrong?

Tomorrow would mark 5 days late (or missed period) for me. I have taken two tests already and they were negative. Granted I did take them at night, but I just have a feeling I’m not pregnant. I’m wondering what the possibilities are for missed period? I’m not stressed, I don’t have PCOS, & I don’t have any thyroid conditions. Is there something I’m missing or leaving out that the doctor could test me for? I’m just wanting to know, what’s wrong? ☹️