Late period

Ok, so my period is now officially one week late and I’ve taken 3 pregnancy tests this week and they’ve all been negative. Pregnancy was the only thing I could think of so now that that’s basically ruled out, I was hoping one of you ladies could maybe give me other possible reasons why my period is this late. And I don’t think it’s caused by stress because I haven’t been stressed at all lately. I know I need to go to the doctor, but I’m just nervous because I’ve never been to a gynecologist before