Who has had luck avoiding pregnancy through “natural planning”? i.e. using this app

Honestly if I were to get pregnant right now it would not be the end of the world. I’m close to getting a degree in the career that I want so life is on the right track and I’m not terribly young. It’s just that when I was on birth control it made me seriously crazy like insane mood swings and I couldn’t even recognize myself at certain points. I just wanted to do natural planning for a little while before trying a different birth control to get myself rebalanced. It’s been 3 months without any form of birth control and I’ve been careful but I was just wondering who has had luck and for how long using an app like this to avoid getting pregnant.