What Punkey said....and be as pushy as you need to be. I don't know how the system works where you are but as a general rule the squeaky wheel tends to get the oil. Don't be intimidated by school staff - this is the time to go into 'extreme parenting' mode.
Edited to add an additional tip: when you're facing assessments etc I found it helpful to write your own detailed report first - what your concerns are, how long you've had them, examples of his behaviour etc. I did this for my son and I was able hand each person I dealt with a copy and not worry that I was forgetting important details each time.