Raw sex with no pregnancy solution solve

I think I might have found a way to have sex without a condom and not get pregnant. I know it’s a birth control method called “calendar method” or something like that. But I’ve use <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period apps</a> to help me. Basically I have sex during my leutal phase which is the 3rd week in your cycle. I monitored my ovulation symptoms and have sex like 4 days after it. Then about 5-6 days later, I have my period.

Have any one ever tried this and did it work for you?

It may not work if your irregular so you have to be very careful.