you're in a great position...make the most of the kids...practice..practice..practice.
Babysit those "little darlings"!!!!
I would offer to help.them going out to do simple tasks, like shopping running errands with them and their children. You'll become very acclimated and knowledgeable about children. When you can change a diaper, make a bottle and settle down another child simultaneously, you've arrived to Ninja Status. They'll all.adore you...
Believe it or not, you're one of the friends they will be the most grateful for. You keep them in the global loop that they would have otherwise fallen out of. And just say, you want kids someday and need the scoop :) Mom's are always willing to share knowledge.
Baby sit, see if you like it (being around kids), then you can talk about their little ones
It's tough being the odd one out. Until you're a mom u still won't understand how they truly feel regarding their kids. But it's great that u want to keep those friendships. Why not go on picnic days or funfair trips with them and kids? Why not volunteer to work with kids with special needs so u can understand mothers and kids better. Some Kids are amazing creatures. Sometimes way too smart than an adult. Their mind on decisions are black and white. Clear cut. Maybe read a book abt a kid and their mom? Remember any judgements you've got on mothers and kids keep it to yourself. They'd slay u if u do. lol