I can sooooooo relate! Your son pretty much sounds like my son. I remember being told I had to go on certain field trips because my son was too much to handle. Penny gives such EXCELLENT advice.
We have sought out friends outside of school. Boy Scouts has been amazing. And can be an inexpensive option that provides a lot of opportunity to create fun memories. The things that do cost money, there are several options for fundraising to help defray the costs. My son doesn’t click with every boy in the group, but he does click with several. He was also able to make friends with a few kids in the neighborhood. Those kids are younger than him, but maturity wise are at his level. Those relationships grew organically but were easier to foster during the warmer months when you might see kids riding their bikes or scooters in the neighborhood. One Mom put a freestanding basketball hoop in her driveway and that attracted a lot of kids.
Those neighborhood friendships are also great when my son’s birthday party rolls around. We started just doing a home birthday party. We don’t make his friends bring gifts or anything, we just send him out into the neighborhood and tell him to gather up his friends. Last year he brought back 6 kids who were all to happy to eat hot dogs and cake. And for the first time EVER, my son had FRIENDS at a birthday party. I had a few confused parents call me wondering why my son was inviting them to a birthday party in 5 minutes …. but OH WELL. LOL. I will not forget one Mom “so just to be clear, it’s your son’s birthday party but he does NOT need a gift?” “No, your son’s presence TRULY is a present”
Helping foster these friendships outside of school has really helped ease the feelings of sadness over not having friends at school. My son doesn’t have friends inside of the school, but he has friendships outside of it. He has his tribe, it doesn’t always need to be inside the school walls.