Hi there.
My twenty one year old son has high functioning autism and please relax.
Like your son, mine was first diagnosed with ADHD, which didn't seem right to us, but...whatever. My son had a launguage delay, but once he started talking he talked a lot. He had social issues too, which is the main problem with autisic spectrum people...communication issues, really. Autistic kids tend to have certain narrow interests and are uninterested in talking about anything else besides them so they get bored with others easily and like to do their own thing. Some autistic kids blurt out inappropriate things or off topic stuff, which makes other kids think they are odd, which they are...sort of. Some make strange noises, which are called stims...or stimming. Or they smack their lips or tap on their desk...more stimming. My son, fortunately for him, learned early to do these things mostly in his room at home. Yes, they can learn these things, although they may never be comfortable, say, at a party with people they don't know. My son is now very friendly if he knows the people. In fact, at work he is often told he is talking too much. My son is such a cool person that I can not even count how many people have told me they love him. He was nominated for an award for accomplishments this year. Yes, he needs some adult supports, but is 90% independent. He does get disability, although he has a part time job, which he is very good at. He does not rage or "lose it" anymore. He is very calm and happy with himself.
Each parent has to decide which type of interventions to take for his child. In our case, we decided that Special Education for reading and math was best for Sonic. He got distracted in large groups. The rest of his classes were mainstream with an aid that was spread out among three other kids. He quickly became the highest functioning child in the Special Education class and a leader and loved helping the other kids, which boosted his confidence. He got a lot of kudos from all so his confidence grew and he retains high confidence today, disability and all. He rarely had to use his aid, but his aid was a source of tremendous love and confidence for him as well.
Sonic always had a small group of friends for lunch in high school...a combo of some Special Education kids and some extremely brilliant nerds who other kids shunned. Together they had a blast and Sonic was never picked on at school. The "typical" kids at his school were used to the Special Education kids and were extremely kind to them. They were mean to each other...lol...but not to the Special Education kids. They loved to help them out and made them feel included. We were lucky. But we had picked this school. Our home school did not have a Special Education room and we didn't like that so we fought for Sonic to go to the other school. They had to pay for a bus to come get him. He didn't mind the small bus. He liked it. Not so busy or loud. Autistic kids, on every end of the spectrum, like routine, calm, and predictability. My son still chooses this, although he now ha his own apartment.
Autistic spectrum disorder is one of the most treatable childhood disorders that exists. We adopted Sonic at age two and were told "we can't do anything for THESE kids." I suspect the psychologist of DCFS's choice said that because his birthmother used drugs and drank and he was thinking that Sonic was brain damaged by it. I cried a river when I got home after that. He was so wrong. Sonic is a hard worker and never quits and is one of the happiest young men alive. He is also a lovebug. Although he doesn't like being hugged (sensory issues) he will tolerate it...lol...and every time we talk, we both say, "I love you." He has been a joy to raise, although not always easy. I am honored to be his mother. He is my hero. I mean that.
Focus on what you can do to help your child grow and learn. Read books. Look at schools and classrooms. Get in touch with an advocate. They are free. Call your state's Dept. of Public Education to find out who your advocate is. The advocate makes a BIG DIFFERENCE when you bargain with the school. The school should provide services for free. If they don't, you need to have an advocate with you to fight them for his legal rights. Don't be scared. Put that energy into being proactive and brave, so that your child can also be brave and proactive and help himself. He can live with this and still be happy and productive.
One last comment: Autism Spectrum Disorders (ASD) kids are often very sensitive to medication. ADHD medications sometimes make Autism Spectrum Disorders (ASD) kids go off the rails. If so, he may do better without medication. My son is much better unmedicated.
Hugs to you. You can do this. So can your child.