First, it is wonderful your son is doing better. I understand your frustration with wanting to have clear cut answers and not getting them. The line between PG+AS or PG+just a bit quirky can be a murky and difficult one. Evaluators can just go on what they have in front of them but it may not be a complete picture. You mentioned you thought NLD was a better fit. In what way?
I agree a child doesn't grow out of ASD but it may be easier to tell as they get older whether or not it is an accurate diagnosis. As they get older they may get improved coping strategies and some periods of childhood may be easier than others. Something disruptive - like a move, a change of school, a death in the family - may reveal they have matured or that they have not. The social dynamics at age 7 or 8 are entirely different than they are at 13 or 14. There can be a reemergence of problems as social expectations get higher and rules are more subtle and difficult to understand. I would also keep in mind that the experience of Asperger's is not just a social one, but also one of emotional understanding and again that gets more complex as kids get older.
If you are seeing someone who understands PG kids and they would like to reassess, I would do so. I would be very honest about how you felt about the last evaluation and share your current concerns. If your son isn't struggling now, maybe leave it six months or a year and do it then. Personally I would want to entirely take it off the table without another assessment. I say this because I've seen too many PG kids with AS really stumble as they hit middle school or as they try to transition to college. If there were still subtle issues there I'd want to know what sorts of supports the child might need.
