My grandson has developmental, behavioral and emotional disabilities. He has an IEP that addresses all of those issues. Until you work with the staff to form an IEP you won't know what it would contain or if one would help.
You will be talking with school staff while forming an IEP which will give you an opportunity to learn what they are seeing and how they are interpreting it.
I suggest that you go ahead with the process of formulating and IEP. You will have input, too. You don't have to agree with it. In fact it won't be utilized until you do agree.
In the meantime, I suggest that you have an independent evaluation. The school will welcome that. My grandson has been evaluated both by the school and a developmental pediatrician and her staff. The two teams work together.
Not knowing what your son's emotional disability is I cannot give you an example that directly applies to him. I'll give you an example from my experience with my 7 yo grandson who suddenly refuses to co-operate in any way. He upsets the entire classroom. His IEP includes plans to teach him how to recognize when he's angry so that he can tell the teacher, in a nice way, that he needs space which they then give him.
My grandson has been receiving evaluations and treatment since he was 2 1/2. It is a process. Your son's testing by the school is just one facet or perhaps even the first step in learning about what he needs. Talk with the psychologist about his report so that you can learn how he arrived at that diagnosis. Tell him why you disagree. Have a conversation. Give the school pyschologist and your son's therapist permission to talk with each other so that everyone gets a more complete picture of your son. It is a process.
My grandson is different at his home, when he's with me, and at school. I'm sure you'll find it's the same with your son. Yes, get another evaluation but don't discount the first one either. It takes a lot of information from different disciplines to determine what a special needs child needs.
It's possible the school labeled your child and now don't give a second thought but I'd check that out before saying that for sure. If you don't talk with his teacher and everyone else who interacts with him you won't know what they're thinking and doing. Communication with everyone is of the highest importance. Yes, it takes a lot of time and energy. Having a special need makes life very complicated for everyone involved.
We have found, that although some of the professionals with whom we've worked aren't the most knowledgeable that working with them all eventually comes somewhere close to what my grandson needs. It's taken many years but he seems to be on track now.