I had a low beta like 6-7 days before my expected period

How accurate do u think it is, I been taking vitex an I'm at CD 33 with no period Glow says it start tomorrow. I'm seriously craving salt an vinegar chips this morning. What do you guys think? Am I out this month do u think the blood test on the day it was done makes it totally accurate.??? By the way did Vitex mess up anybody cycle please share anything u can share with me.. Thanks Ladies!