I hear ya.
My girl doesn't like talking kids/marriage... sometimes I will talk about what we should name our kids... and she freaks out - it's great!
Once after one of these jokes and her freaking out I said - "C'mon, just look at my past relationships and me running away from commitment on every one of them - do you really think you have to worry about me popping out a ring?"
She immediately gave me a big hug and a kiss - Lol, I found a good one
You don't know it yet, but she's got you right where she wants you.