I’m definitely late

Alex

Me and my s/o have been trying to confirm 3 months, last month my period was 2 days late. So far this month my period is 3 days late. I thought I was getting ready to start cuz I was cramping and cranky, but it still just hasn’t started. I did test and it was negative, I would be 16 days past ovulation. When would the test come up positive if I was ? I really hope I don’t start!