Extreme Tokophobia

I have extreme tokophobia. To the point where after sex, I count the days as if I accidentally got pregnant and see what day I would be on and progression of the “baby.” It has taken over my life. I search google endless hours ready all these horrific one time instances that have happened to women. My parents had me when they were 17 so my whole life I’ve always been told don’t get pregnant young or no sex allowed. They would threaten to take me to the doctor once I got into a serious relationship. It has emotionally scared me. I’ve been with my SO for 5 years now and I find it hard to enjoy sex whenever I do give in. I’m always in constant fear that I may accidentally get pregnant. Even though I’m on BC and always use protection. I don’t know how to overcome this fear and I don’t think therapy will help.