how to stop being nervous

I am in love for the first time with a man who's a little older than me who loves me back (literally writes me love letters every few days) and we've started to have sex. I'm not his first but he's mine. He is absolutely so safe when we have sex. He gets the best condoms he makes sure they are safe and quality and the correct size he pulls out and I'm on the pill which I've taken every night for 6 years. (I'm 18) but I'm still so scared that I'm pregnant. It also doesn't help that I never get my period actually. How do I stop from being so scared that I'm pregnant every time?