No, I don't think you are. I never thought I'd not have children of my own while I was growing up, however, as soon as we got engaged and it became a distinct reality that I might be expected to have a child in the near future I thought about the implications and realised that I really didn't feel like I could go through with it.
My husband knew about this before we got married, and while he still wants a child and hopes that I change my mind, he's not pressurising me to do so. We've discussed adoption but he, like your partner, isn't interested in raising a child that isn't ours.
For me, it's the thought of my body changing and never being the same again. I'm comfortable in my own skin the way it is, and while it might change as I get older, that'll be a gradual change rather than over 9-months. I'm not 100% adverse to having a child to look after, but I don't crave one enough to feel prepared to put myself through something like pregnancy and childbirth, if that makes sense? From reading forums, I know that people who suffer from tokophobia say that they'd cope with a c-section, but frankly that scares the life out of me too, probably even worse than the thought of a natural birth.
Anyway, sorry I've not been of much help, but I thought it might help to know that you're not the only person who feels like that. It made me feel a lot better to know that I wasn't alone when I started to research all this.
I guess I'm constantly being reminded about children because I've hit the age when everyone I know is having theirs, so it's a constant reminder on Facebook etc...