Is glow accurate???

Heather • Nursing student, raising two beautiful boys and have a loving hubby! I`m the queen of my own castle!
So glow said I was ovulating last week well I don't think I did... I followed another app and it said my ovulated over week ago. My period was September 13-19 very light then that would put me ovulating 28th of September to October 1. So I BD every other day and now that would put me at 12dpo. I am having slight cramps and I am nausea. Could glow have gotten my ovulation wrong. Need help. Thanks ladies