The Glow app doesn’t make sense! What am I not getting!?

Br

The predicted ovulation dates are WAY OFF! I made a fake “perfect cycle” just to see, and it was so wrong! Period ended, positive opk 14 days later, temp shift following day..... and it predicts I ovulated on like cycle day 3! Huh!?!? NO SENSE!

Same for the chance of pregnancy percentage. Even in my fake “perfect cycle” scenario above, added sex hearts to every day around the O day and it says Low Probability Pregnant 2.5% chance. What!?

Anyone?