I think I’m a bit like you since I do that too. Everyone (even at work) knows that I don’t want to see baby pictures and I’m not excited about a baby. I don’t think much about having kids but parents usually really really love their kids immediately, even before they are born, and if they are close friend or family then I am ok vibing with that for their sake.
The only time I’ve actually felt positively about it is when my best friend told me they were having a baby. It took me a moment but I thought then felt that I was able to be happy because he was happy and his partner (who I also like) is happy, and then it took me a few days of thinking about it that part of me was also picking up on this excitement because I wonder what my best friends kid will be like. And it’s only because I care about him and his life a lot. I’m not close to my sister and have never felt those feelings before about babies/parents.