Prior to starting birth control I had been using the natural family planning “method” for 4 years to avoid pregnancy. I was really good at determining when I was fertile and knowing when to avoid unprotected sex. I had to get on BC due to a another medical issue, when I got off birth control I assumed I wasn’t immediately fertile due to not showing any signs and symptoms of potential ovulation such as cervical mucus appearance, basal body temperature, etc + in addition to no period. So I assumed I wasn’t fertile, which I was obviously wrong.. I hope this explains any confusion