Curiosity Question Regarding Irregular Periods

Hi so, I tend to have my period every 2-3 months rather than every month. I've done a lot of research regarding ovulation times, the pill, etc. Due to my young age, my doctor says that me going on the pill now could possibly lead to infertility later on in life, especially with my irregular periods, allowing me only 6 times during the year to get pregnant. My boyfriend and I are planning on having sex for the first time (I'm still a virgin and so is he) relatively soon. We will be using a condom with spermicidal lube as well as the pullout method. I believe using all these together will be an effective method to preventing pregnancy but just for my own personal anxiety, I kinda wanted something I could keep track of myself. I've read a lot about fertility and ovulation times and I even bought myself ovulation tests (the pee sticks) to see when I'm ovulating. But for someone with such an irregular period, when should I be testing myself? When does ovulation usually occur in the cycle? Any help is appreciated. Also, do you think with all my forms of birth control, my boyfriend and I will be safe and I won't get pregnant?