J.L.
Get out of the psycho-therapy trap now. Find a support group in your area with other families of high functioning Autism and spectrum kids. You'll be better off for it. Right now, it sounds like you're putting undue pressure on yourself and your child to conform to what others think are normal behaviors for a young kid.
While it is indeed exhausting keeping up with a kid who is slow to read social cues, they aren't beyond hope...and they certainly aren't mentally ill, so why go there?
It would be more beneficial to all of you to go where the kids are all on the same playing field and the parents are all experiencing the same challenges, and in that setting give your child the chance to grow socially without judgment or others jumping to conclusions.
He will eventually learn to sit still and read cues. But it has to be on his developmental timeline. Don't worry. I sense worry and fear. No need. Just find a place where you and he can find your groove when he's developmentally ready for it. Being with other families like yours will provide new friendships and a support system so you won't feel so out of the norm. Best of all, you get access to resources such as socialization classes, sports, theater, and other fun activities for your family to enjoy without having to worry about other's judgements.
Here's a link. I'm not in your area, and these might not be near you, but it might be a start of where to look. I'm sure if you called, they'd know of groups near you.
http://autismmclean.org/resources/supportGroups
http://www.autismspeaks.org/community/fsdb/category.php?s...