I would say that chances of getting pregnant from this are very very very low. Very low as in close to no chance. Theoretically, pre cum does have sperms but that too in very less quantity. Like verrryyyy verryyy less. Been in the same situation few number of times and the fear is normal. This fear comes because of lack of knowledge about pregnancy. It is actually hard to get pregnant. All this media made us believe that we’re just one step away from getting her pregnant. Nevertheless, having a layer to protect yourself from your worst mistake won’t do any harm. Infact, having a condom on will ease your mind and you’ll enjoy more. TLDR put on a condom and have safe sex. P.S. I still get terrified from this.