Yes, you're rattled. And you'll be rattled again so you may as well get going with a coping strategy.
There's no denying that this process is bloody awful, and you'll find it very stressful as every step requires you to imply that the people who are supposed to care about the wellbeing of your child, and worse, ARE working with your child, are not doing a good enough job. No way do you want that relationship to deteriorate, and yet, how can you put your needs for a happy relationship before your child's needs for adequate provision.
And often, these people don't even KNOW they are doing a shit job because all the professionals around them, on which they base their own self-worth, are telling they they're bloody marvellous.
I would put in writing, a request for both the school file and an additional 'subject access' request for all information they hold on you or your ds, including emails and handwritten notes.
I would also send the same request to the LA listing the departments with the caveat (And any other departments that hold date on us). And then send one to the Trust that governs any SALT or OT.
They may feign horror but they are more than used to replying to these requests, so don't be put off. Christmas is your advantage because if you put in the request now, they might not be bothered to spend the Christmas hols weeding out the stuff they don't want you to see.
This action might not just get you an assessment but a statement of half-decent quality because they have been warned that you'll tie them up in paperwork exercises if they don't.