2 weeks late but bfn

Hello! Wondering if any other woman in here has gone through the same as I. I quit smoking at the beginning of October. My period after that was 12 days late then the next was normal and now I'm 14 days late but the test reads negative. I'm not trying to get preg and the only thing we have done to prevent is pull out. I'm 28 and am hypothyroid if that makes a difference. I have 2 boys, 9 &6. Anyone with any experience with this? Or has any idea of what's going on? Can't go to the doc till next week. Thanks for any help I can get!