Avoiding pregnancy at the moment

I’m getting married June 2019, I just stopped taking birth control have been on it for 10 years, I stopped last month due to they stopped manufacturing mononessa and i did not want to switch to a brand I didn’t trust based off of reviews.

How well does this app work with ovulation? I would like to avoid getting pregnant before marriage as well as I have hypothyroidism so getting pregnant isn’t a walk in the park.

Can I trust that I’m ovulating based on this app? And the risk factors of not getting pregnant when it says so ?