How can I assure everything will be ok?

I’m with my first ever girlfriend, I’m fairly new to sex she’s been the only woman I have had sex with. I have a fear of pregnancy, probably because I don’t want kids. I always wear a condom and she’s taking birth control. But every month, I have a fear she is going to miss period.

countless people have told me that what we are doing is safe and there is a slim chance she will get pregnant. I’ve had this conversation over and over with my girlfriend, but it frustrates her because she keeps telling me she’s not going to get pregnant. Is our method pretty good? How can I get over this?
How can I assure everything will be ok?
Add Opinion