Unreasonable pregnancy Paranoia.

Hello doctor. I am always having a unreal Paranoia about pregnancy when I make out with my girlfriend. We used to make out regularly when in Jan 2020 her periods got delayed and since then I have become paranoid about it. We have never indulged in any risky behavior as far as pregnancy is concerned. Because of my Paranoia, we did not make out till Nov 2020. I thought I will be fine now but since the makeout I'm again getting those feelings. I am so paranoid that I wore 2 underwears and my pant and didn't even let her touch me near my crotch. I am having feeling of helplessness and it really takes over my life and I can't do any productive work any more. I want to get rid of this paranoid feelings once and for all. My girlfriend is also getting irritated with me every day. What techniques or methods can I follow to get rid of this feeling? I am tired of constantly feeling stressed.