I just had twins over 6 weeks ago but terrified of having sex again in fear of getting pregnant

My doctor has cleared me to have sex & I’m on birth control .. but I am so terrified of getting pregnant , it’s like I can’t even enjoy sex with my significant other anymore because that’s all I think about. Is anyone going through this or have already been through it? I use to love sex & now it’s like I don’t even want to have sex in fear of getting pregnant. Ugh ! It is so frustrating.