Cd 36 no AF BFN

Hello

My cycle length is 33-35 days, I have been cramping ( on and off) since last 2 days but no AF yet. I don’t track my ovulation via tests. My first day of last period was aug 19. I test hcg (cheapie rest) yesterday in evening, but I didn’t hold off urine for 3 hours and also drank water , bcz I thot I missed period by 1 day, so hcg should be enough to show up in random urine sample. Also if AF doesn’t show up for next 4 days, ie 6 week from last period , would it be a missed period ??