I'm in my early thirties and adamantly childfree. I'm lucky enough to be in a long-term relationship with someone who brought up her desire to be childfree on more or less our first date. But I am not having too much luck with my friends from childhood and university - they all seem to be wanting kids, and learning of their pregnancies leaves me with a feeling of sadness. I don't hate kids and think no one should have them, and I am happy for them if they truly wanted this, but I also know what them having kids will mean - we are essentially putting our friendship on hiatus, and I still don't know whether waiting 10 years for the kids to be a bit more independent and not requiring as much attention will mean I suddenly have friends again, but somehow I very much doubt it. And I also don't want 10 years without other friends than my girlfriend. She is in very much the same situation, and while we are good at making the best out of not having kids and stressing about having them, we both would want to be able to hang out with good friends once in a while, both common between us, but also some that are exclusive to each of us.
My assumption is that this is quite common - so I am hoping someone would like to share some success stories in turning this situation around. :)
You seem to be in a situation where your current friends will be less available, leaving you more room for additional friends!
Find or continue a hobby (on your own or with your partner), meet some people, make some new friends.
Also, don't abandon your current friends. Keep talking to them, remembering their birthdays, etc. Keep trying to do stuff together, but just respect that their schedule will be heavily restricted and do your best to work with that.
Your parent friends can focus so much on how the kids are doing, that having someone who cares about how they are doing is also extremely valuable; be that friend!