I’m a bit older than you, (I’m 42) and at 40 I did have an “omg, am I sure about this no kids thing?” in a way. It passed pretty quickly when I realized I am sure. I like kids, and I have a “nephew” (my best friend’s child, since I’m an only child, as is my husband). I like my life, and I am fine with the choices I’ve made. I wonder how my life would different if I had chosen differently, and mostly I think “yikes! no!” So that’s good. I’m lucky, too, that I’m in a field (academia) where people don’t ask about kids after the “do you have them” small talk thing. When asked why, I simply say that we don’t want them. Or I say that I’m too selfish and don’t want to spend the rest of my life resenting someone. :) That often backs them off a bit.
This was a great piece, and I wanted to say “right there with ya!”