Knowing your cycle.

I know this is risky but I'm really thinking of just relying on knowing when I'm fertile and ovulating and condoms. I've tried most forms of BC and they all upset my bladder to the point where it feels like a UTI every single day and night. It's a terrible way to live! Just hoping to get some advice on how to master my cycle and if this app is also good to rely on for that when used correctly. Anything would help! Like I said I do not want to be pregnant right now, but my doctor can't figure out what to do. If anyone goes this route what do you think? Anything would help ladies!