I have Glow and Ovia that I am using to help give me more insight etc. They're not predicting my fertile window the same. Ovia is almost a week after glow. I calculated my cycle and my fertile window should be 10-21 days from the start of my next period. My cycles are between 28-32days. Also, if I do not get a BFP this month I'm going to buy some OPK. What brand does everyone like and which are the most accurate?!