How do I actually know for sure when I’m in my fertile window? I log on two different apps (Glow and Ovia) and they are two days off from each other. Ovulation is also 2 days off...one says the 18th and the other says the 20th. So how do I actually know for sure when I’m in my fertile window because obviously I want to BD every night of my fertile window. I do temp and do OPKs but obviously the OPK doesn’t tell you until you surge which only gives you a day or two of BD. Help!