I'd disagree that people who don't have kids can be incredibly shortsighted - I'm 35 and have none and would say many people with kids can be very shortsighted and fail to imagine what life's like for anyone else once they've had theirs ; )
It does sound like your friends haven't adapted very well to the fact that you can't go out etc. But they will or else you will find news friends as others have said, whether or not they have children - they just need to accept that you have and vice versa.
What I would say, from the perspective of someone who has no children herself but has many friends who do, is this ...
Everybody changes through life whether or not they have children. As people have said, your friends didn't choose for you to have a child nor the massive life changes that come with that.
My most valued friendships are with people who have children, as it happens, and that is because our friendship is strong enough to survive any other differences in lifestyle and because we have each made massive efforts to adapt to each other, efforts that go both ways. I go to theirs when they can't go out and they equally make the effort to stay the night with me and I cook dinner and we open a bottle of wine. They invite me to go away on camping trips with them but don't expect me to babysit. If they need me to babysit they ask nicely and respect that I am also busy and have a full life (though they know I would love kids of my own and am sad it may never happen - it's not a God-given right). But I like helping them out where I can. The kids love coming to mine and my life is richer for having them in it. Me and their parents love hearing about each others' lives, though occasionally we are jealous of each others' lives and occasionally the differences show and we fail to understand each other. But generally it works and I treasure those friendships, children and all.
I am having trouble with an old friend who has a small child and has always assumed since that everything should revolve around her and that I should make all the effort. I don't have time for that and other friends have shown me it doesn't have to be that way. Her outlook is quite narrow and selfish.
I have purposely distanced myself from other friends I once valued very much because I can't have only friends with children in my life as I would feel like I was the odd one out all the time and at one point in my late 20s/early 30s I did feel that way as it was happening all around me and it was very tough. I imagine I will reconnect with some of these old friends more when their children are older, though we will all have changed more by then, I guess.
I think the key is trying to imagine what it is like for each other and going from there. Not all friendships survive the massive changes that having children brings but you made those massive changes - your friends didn't, so be easy on them and don't assume they have more trivial lives or a lesser status or are somehow less mature just because they don't have children. We all need each other as a society and we all grow in our own ways. Some of us grow more through not having children than from just treading the well-trod path of others. It all depends on the person and I don't believe (any more) the rubbish about how having children makes you 'see the light' in a way no one else could ever understand. But of course it's a unique experience, one of many in life.
It's brilliant to have kids and be a mother (or father) and it's an incredibly important and difficult thing to be, but don't make assumptions about those of us who don't - that's my plea to any mums or dads on here.
csemum - I hope you and your friends can continue to have great times together even if it's different. Maybe it all just needs a bit of time and imagination from all sides.