Hi, sounds very frustrating. Sorry you are going though this.
I don't think you will like my suggest but stick with me though this ... change schools.
So I have a child with a diagnosis of ADHD and Autism, to be honest it's just a label and not sure why the teacher thinks that would solve anything. My child was violent, he paid throw things, bite (to the point we had to start him having a course of hep b injections), scream, run away, he would self harm and generally it's was impossible for the school (and is to manage). He attended a pupil referral unit, the youngest child they had had at the time, it was awful. School were resistant to take onboard anything I said and if I pointed out behaviour was caused by something (like playing music to trigger tidy up time) they work just tell me that everyone else in the class enjoyed it and he needed to learn to conform.
It was hell. He was hell. When one of my others showed signs of SEN (although total opposite of his brother and wouldn't harm a fly) I just really struggled. There were numerous reasons for wanting to move but the biggest factor was I wanted to see if a school with better training and resources would help. It wasn't easy, the school we decided on and moved to be in the catchment of, were very resistant to accept him given his issues, which meant he was 9 months out of school with 4 hours home tutoring a week. It actually turned out to be a god-sent miracle. She focus on proving him with successes. She did work well below his capabilities which is drastically low anyway, but she wanted him to experience feeling successful. At this point he was 7 and couldn't read, write, his maths was very very basic. It was shocking because all we had done for years is concentrate on his behaviour.
He started school in September 2018. He has never once been in trouble, he has lots of friends, he's completely caught up with all his work and working within the expected level for his age and even above sometimes. He's never laid a finger on anyone, never thrown anything. He is very very well liked. His teacher cried when he moved up in September and regularly comes to visit him and him her. His new teacher and teachers assistant are the same, they adore him.
It's such a shocking difference. The only difference was sometime taking the time to believe in him. I think as a mother I made things so much worse, when he did something wrong at school we would tell him off at home , school would tell us we had to take treats away from him as punishment and so we would.If I reflect too much on that time I truly hate the mother I was, I so wanted to fix his behaviour and support the school that I didn't realise the damage of constantly being told off did. Even when we praised him for good things, it was shrouded by the bad things too.
The point was school wanted him to conform. But they were unwilling to accept he couldn't. In comparison the current school talked to him and me about his struggles and came up with plans. For months he didn't attend assembly as he couldn't cope, then he would attend for 5 minutes and his teacher would sit with him in the floor and leave when he needed to, it's very slowly built up and now he attends with everyone else and you wouldn't ever know there was a problem.
Don't get me wrong, I think my currently school do far far more than I would expect anyone to do. They really are outstanding and I do a lot of work at the school and volunteer as I am so grateful for everything. I wouldn't have expected anywhere near the level of support they give to him but it has been so worth it. Is incredible the change. When the school was inspected I asked them to read his statement (we are in Wales so still have statements), then meet him. They actually asked to see me after because they couldn't believe it was the same child.
Sorry about the novel.
My other child saw CAHMS recently too, who on paper meets the criteria for ADHD but they didn't feel it fitted having met him. He has some significant issues but he will sit for hours spinning a wheel or sucking his thumb (he's 7), and it didn't really meet their or my expectation of ADHD, they also did a class observation although I am not sure how that went yet. Feel free to message me if you have any questions.
My question to you is, is the only "difficult" behaviour shouting out? Does he do that at home? What have school done to try and manage that?