Hi! I didn't want to press that "reply with quote" because it'd make the thread too long! It doesn't sound like your kid has any behavioral issues. That's good!
Your son has moved around an awful lot the past three years. Plus, he's been laid up with a broken leg. I'm sorry for all of this. I know how much a consistent environment means to a kid. Your son doesn't need a lot of friends, he just needs ones or two.
The onus is on you to reach out and make those contacts. Who cares if you're not rich? The best way for you to meet people under this circumstance is to make yourself needed.
Volunteer at the school. If you work, then volunteer at weekend and evening events. Become the team Mom who brings in the cookies and always ALWAYS find someting ice to say about everyone (I don't mean kissing up, I do mean greeting them and maybe even remembering something about them. "How is your dog, Mrs. Jones?" Join the PTA, help raise money, organize projects for the teacher. The more you're seen, the better it will be for your kid.
This might take a little while, but if you start in September, if you consistent in your efforts, if you don't let yourself get swept up in ANY gossip about anyone else but are positive and outgoing, then by June you will win people over to your side.
It's true, you may always be the one organizaing events at your house. Other people may not be as considerate as you, but there's nothing you can do about that.
But what you can do is be upbeat, positive, outgoing, and slay any naysayers with kindness and effervesence!
One more thing.... keep him away from toxic adults like your brother and sister, until he is more secure and has made friends. None of you needs them!
Smile and slay, sister! Smile and slay!