Fertility window

Since I added new information in on the 22nd my fertile window is changing every day on Ovia which is the first calender but it hasn't changed on Glow. Which calender seems more accurate? Ovia allowed me to put my mc information in from March, I started using the app on April 15th so I don't have previous data. I don't get it.. haha. My fertile widow is getting smaller and smaller according to Ovia.