She probably knows and doesn't consider it a big deal. My wife knows and sometimes makes fun of stuttering people but what I've noticed is the fact that non stuttering people don't see it as anything more than a minor inconvenience. They don't understand the lifelong trauma and suffering related with stutter. Your best course of action would be to explain to her how that makes you feel. And why she shouldn't say these things. Don't overthink about it dude, trust me.