The Boy and I have been married for almost 17 years (together for 23, OMG!), and there were never children on the radar screen at all. Don't be pressured, by the way. I have no regrets, and neither do any of my child-free friends, who range in age between 35 and 60. We're all having fun.
Maybe you're hanging out with the wrong pregnant crowd? When my friend first found out, she told another friend (tearfully, because she was still in shock), "Messy's gonna hate me now because she doesn't like babies!"
I was able to reassure her that I like babies just fine, especially when I can hand them back to their mothers when they start to get a little ripe. My Cool Niece is now 9 months old and cute as a bug. Also she's walking. She gets better at it every day. Soon we'll have her on a leash, she moves so fast!
My friend is part of the mommy crowd that likes being an adult. She worked at home while on maternity leave because babies sleep a fair amount. She went to a group for new moms where everyone was talking about baby-related stuff - the best diapers, the best nipple cream, the stinkiest load the little gaffer ever dropped, the perfect stroller....and she had to leave about halfway through the second meeting. She described the conversation as "gag-worthy".
Feel free to ignore the weenies that tell you you're missing something. If you don't want kids, then you're missing nothing. As for pets, they don't want to go to university, they never need braces, and they don't need your attention 24/7. When your friends are paying for all that, you'll be safely retired.
If anyone tells you that that's selfish, tell them to get lost. I've always thought that criticism was larded with just a hint of, dare I say it...jealousy.