Please help! Need advise!!

AF was to show her face on Oct 6th and still nothing. I experienced a little cramping last week and a little today and yesterday! It's like I'm gonna start but nothing happens. So AF is 2 weeks late and still getting BFN's! I do have an appointment on Thursday w/OB but I just wanted to know if anyone experienced what I have and got positive results from blood test? I'm so confused that it stresses me out and don't know if being stressed is the cause of no AF?