Ovulating apps

I have two <a href="https://play.google.com/store/apps/details?id=com.glow.android">ovulation apps</a> and a <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period app</a> which I'm using. All three apps record my period but give me three different ovulation dates. My husband and I just started trying to have a baby, I'm a little confused to which app I should be using... We have used all three different dates just to make sure I haven't missed the window. Any advice on this would be greatly appreciated. ☺️