As the title states. We've been together for 3 ½ years, but because of many reasons that there's no real need to explain we haven't had sex that often. She's my first, and since we got together she has insisted on doing it without any protection: at first I refused since she's still regularly (more or less) on her period, no sign of pre-menopause whatsoever, and we already fought about it back then... then, because I lacked the needed self-confidence, I gave in and decided to trust her. Nothing has ever happened after that, but I did feel uneasy everytime... until recently I decided to step up again, first by saying again that we should use protection and today by refusing any penetration otherwise.

She got really upset, stating that I'm thinking too much and that she "knows" when she could get pregnant and that, at 51, there's no chance anymore.

I know that the chances are really slim... but, since there's no sign at all of menopause, I'd rather have an added precaution: "slim chance" doesn't equal "zero chance", and in case it happened we can't just shrug it off. Furthermore, she's told me recently that, in case she did get pregnant, she'd be 100% against aborting.

Am I overreacting?