I've managed to hit early middle age friendless, childless, husband/boyfriendless, with just my two kitties comprising my little family, so I think I understand what you're dealing with. Members of my peer group are married with kids and haven't gotten to the grandkids stage yet, but I'm definitely on the outside looking in from a social perspective.

Extended family isn't always a blessing...I have aunts, uncles, cousins, etc., but I never see them because they're even loonier than I am

I don't have any advice for you, but feel free to drop me a line if you ever want to chat with someone who's in a similar situation.