8 days late with neg tests....

So I'm on day 8 of no af. Some minor cramps. Spotted a light watery red for 30 mins. Med to heavy creamy cm.Took 3 home test and they all say neg. Called doc and she said no worries. That I can go 3 months w/o af. I've never been late besides when I had my first child. I'm concerned. Has anyone else had a late bfp that sounds similar to my story. Been ttc for 9 months. Doc also said if I'm not pregnant by nov she would then step in and help....