I need to add, you also need to make sure this is a lifelong deal for your son.. He is not going to be "cured" or "snap out of this" if anything he will even have to be more aware as he gets older. My husband is ADHD and as he has matured in age, it has gotten worse. He is successful at his job, he is very creative, he has a ton of friends, but I have to help him manage certain things, with reminders, notes etc., I love him for who he is and I am willing to help him in any way. And thank goodness he puts up with me.. I think many people think once these people "grow up" they are some how "Cured". That is just not going to happen. It is just different from "the normals" whoever they are.
I am so sorry. I think part of this is that your mom is not educated about these diagnosis.
My nephew is also "PDD-NOS (autism, he's high functioning) and ADHD "
My SIL refused to discuss it in the beginning (and still acts like it is some big damn secret) and so we were not sure what to do when around him.. He was late speaking and would grunt for things. I was used to giving our daughter the "words" when she did this at this age. My SIL took it as being rude or not doing it right. I was just trying to treat him like any other child.. Because she did not let us in on where he was and how she wanted us to treat him she took offense.
I am sure she saw or felt we were thinking she was not doing a good job, but honestly, she never shared what he was working on in therapy and what the goals or expectations were.
My MIL was "in, on what was going on with his therapies" but the rest of us were not privy. It made us all tense.
I wish SIL had sent us some tips or some goals or anything to let us in on what was the best way to help or to expect with her son.
I have never been good at reading minds and it also made me feel like I was irritating her, but I just felt clueless and left out of the loop.
FYI, This nephew is now in High School, plays the guitar, writes music, plays football. The girls love when he attends the dances.. He is willing to dance because he is not self conscious!
Hang in there and speak with them about where he is, what the goals are for now and long term, and the best way to help him in different situations. You have had to learn this, so will everyone else that loves him.