my son was diagnosed without an ADOS, perhaps children that have more obvious symptons do not require it? havent got a clue. the only part of the paeds letter on my sons diagnosis that was not just repeated stuff i had said was her 4 line conclusion . Reading that 4 lines made me feel quite sad really, its horrible reading about your kids isnt it. Perhaps give them a ring if you have questions, ive always been quite forward with chasing people up or you can ignore my morning waffle and hopefully someone else more helpful will reply
if they've put it in writing that he's got ASD then don't think you desperately need an ADOS. since you've already got a diagnosis, ADOS in this case would look at how far along the spectrum he seems to be, whereas your boy is so young that there's so much scope for change/improvement. I would defo phone up though, as if this is main diagnosis letter then some one in the future might nitpick if it's not signed. I would also ask about future review arrangements by the doctor.
my son was dx at three by the paed alone (after 3 appointments), I asked about the testing but he had no doubt using the triad of impairment he was clearly autistic. I asked about would he need further testing and he said if I wanted more detailed report when my son is six i could start pushing for a test for when he is seven, but tbh I agreed with paed why put my son through this.
DS was dx without ados last year on NHS but passed it in a private clinic that did a holistic review few weeks ago.
Was the dx given without good/inadequate multidisciplinary observation he had for 7 months (even there it states speech as primary concern to address) or was the VB, RRT, Sensory integration and all the hard work I put the last year that helped him pass - I will never find out I guess.