OPK says not yet but BBT says already done and gone

Angela • TTC for first baby and trying to stay + 😉

So I got a Femometer last Friday and I started taking my temps on Saturday morning. Sunday I had a “spike” in my temp though I took it later than I did Saturday but definitely before my feet hit the ground. Now my Femometer app is say I ovulated Sunday. I’m also using CB Advanced OPK and it started reading high chances to get prego since 9/1. Glow predicts that I’ll ovulate tomorrow 9/6 and my other app (Flo) says today is the day. Luckily we’ve been baby dancing all throughout these days. My thoughts are that Sunday’s spike was a fluke. I only question it because I felt a little crampy Friday and Saturday.

Who should I believe? Lol