Ok. I am prepared to be flamed.
Your son is getting a lot of attention from you about his bad behaviour, he is / has been assessed for a variety of things, he has been tutored, there have been meetings about him at both schools he has been excluded etc etc. An ed psych suggested that he has low esteem, I wonder if your son has fallen into the role of naughty boy at school, it gets him a lot of attention, albeit negative from the school and other pupil, it means he gets away with poor behaviour , rudeness and attitude, all without much effort, it also , just as importantly gets him a lot of input and response from you.
You might well have missed the bus with the present school, there are only a few weeks left, but I think you should be working on his self esteem and view of himself as a learner, and I think one way is by making sure that the attention he gets from you is attention that is not based on him as a disruptive child.
Stop reinforcing the deficit attitude that he is dyslexic, dyspraxic,autistic or any other ic since he clearly is not, I think you have set a self fulfilling prophecy in place, and instead of contacting the senior school and flagging him up as a disruptive child you should be working on raising his self esteem, showing him that you can be proud of positive things in his life, developing a relationship that means he is trying to do the right things to win your approval rather than doing the wrong things to win your attention.