Late AF

Has anyone not gotten a BFP until a week or later after your missed period??? I was 3 days late for AF and only spotted for 2 days which was brown and barely enough to wear a panty liner for. I called my GYN and she said that this could’ve just been a light month for me but to test again in a few days. I know it sounds crazy, but my body just FEELS pregnant even though I’m getting negative results. I hope someone can give me some hope here.