First off - I'm a psychology major becoming a doctor of neuropsychology - and I have ADHD - I hope this is helpful as I'm listing some treatments and such at the bottom of this. I've graduated from the Naval Nuclear Power Training command and am currently becoming a doctor of neuropsychology, am a dad with two children...all with ADHD....life's tough with ADHD.
You didn't state what exactly you're having a problem with, so it's hard to really tell you what to do in terms of everything.
But it can be dealt with. Here's what I've learned in dealing with the ADHD aspect.....I won't touch the sensory integration aspect.....
You talk about disagreeing with the assessment.....
ADHD has many "criteria" to define it.
I've found a couple things in researching it:
Generally, we see higher assessments of boys with ADHD than we do girls - some psychologists attribute this to the fact and tendency for society to be more forgiving of girls than boys. That can make a difference because boys are naturally more rambunctious than girls - and teachers aren't trained in doing psychological assessments and I see many get frustrated with boys more often than girls, especially if the instructor is a woman, I see the statistics for this in the psyche journals as well. We do see a higher number of women willing to label a boy ADHD than we do see men - statistical fact - does that mean they are wrong? Not neccessarily, but it is something to be aware of as well as a teacher isn't qualified to make such an assessment. I've seen some male instructors better able to deal with an ADHD child than a female instructor so that despite the child's impairment, they functioned just fine in the environment with that instructor and went on to be successful.
You also didn't state what the age of your child is....that's important too. If they are 5, 6, 7, they may have a different prognosis than if they are 13, 14, 15 - although you stated your youngest is 13.....
Psychology is often about "labels" so people can know what to do with something - those labels are easier to work with than a set of symptoms repeated over and over again. However, here's an example of the criteria for ADHD from the Diagnostics Statistics manual of mental health - if you read it carefully - (read it, it's interesting! and quite short) you'll notice that there are various combinations of behaviors that all fall under the same heading, which means, you can have 20 children with ADHD and not one of them be the same, due to different combinations of symptoms! Each ADHD child is different! Which is what it sounds like you're noticing and the doctors may not have explained....provided he has ADHD.
http://www.behavenet.com/capsules/disorders/adhd.htm
A very important aspect of this is duration - what is the history of this? Did it start suddenly or has it been ongoing for years? Also, it's important to note, that the main criteria for an assessment is "impairment." I.E. I have ADHD, but I have learned to manage it and function perfectly fine! Does that mean I have a problem?
***Here's a bit of psychology with ADD****
ADHD also has to do with several biological factors in the brain and brain chemistry. In short, ADHD can be an emotional issue for the child - they can have mood swings - forget things - not understand things - not pay attention to things - run around and be hyperactive - and all have "ADHD." I've experimented with myself and found that - since I do have ADHD - that megadoses of Vitamin B Complex have smoothed me out considerably.
Vitamin B Complex helps regulate our emotions - ADHD being an emotional issue - children LIKE things LOVE things HATE them DISLIKE them - Vitamin B Complex alone has seriously leveled me out and I've seen it level others out remarkably so they can function and go to school.
I also take Focus Smart - a concentration supporter like Focus Factor, I take that in place of prescription medication and so do some of my friends with ADHD and now I have a 4.0 at the university, I've got a piece of research that's up on the national level for review for assessing convicted sex offenders.....life's great, though I still struggle with ADHD I function quite well compared to what I do without it.
You haven't described any symptoms, and I'm not sure if your issue is only that you have two conflicting opinions.
It's important to note that you can have two overlapping issues as well....ADHD combined with something else....that's important to recognize as well.....
My advice?
Get a second opinion that isn't the teacher - or maybe a third opinion. I'd reccomend a therapist trained in dealing with ADHD or a neuropsychologist also trained....
Good luck!
~M.
Eventually to be a Ph.D.
(I don't know if this answers your question, but I hope it helps...)