Oh this thread is so sad
You all sound so lovely too. I have a couple of close friends, but apart from that I don't really have a social life. I don't chat to the mums at school, although did meet one years ago that I still talk to now even though her ds moved schools.
I drop ds off in the car and he goes in alone (he's just leaving yr 4), but when I used to go in with him, I never bothered with the other mums.
One thing i can say, when I had dd 12 yrs ago, I went to lots of mums n toddler groups to try and get to meet people, but never did. I have found that the people I did meet along the way never required hard work at the beginning, ie going out of my way to be nuice just so I could see if 'this one' would work and become a friend. Honestly, you don't have to try very hard to be nice, if people are cliquey and unfriemndly, they are not all of a sudden going to be nice just because you have gone over and made an extra effort...so don't bother as you will only put yourself through stress.
As the kids get older that feeling of isolation disappears, when you take child to activities and they can ask people back to yours etc, your social circle will automatically get wider.
Just remember if it seems hard work, don't bother, it should be nice and natural!