AF a week late and negative pregnancy test

I had a miscarriage in August and AF was normal for two months, the third month "now" AF is a week late I have taken five pregnancy test all negative. I took the test different days and they were different brands. I have never had theses problems before, AF is consistent. I made a doctors appointment but they can't see me for two weeks I'm so nervous!!! I have also been experiencing cramps it feels as though AF is here but when I check nothing!! This is driving me crazy!! Has anyone else experienced this? Or know what could possibly be going on?