The psychologist my son works with specializes in autism and giftedness (along with anxiety disorders and adhd). She did her dissertation on the topic and spent years working in an autism assessment clinic. Her practice focuses on working on social skills with kids who have ASD and/or who are gifted. So I trust that she has the right experience. She has also spent a lot of time with my son in various settings. She is confident it's not autism and has said that doing a full evaluation would be a waste of our time and money.
For another perspective: the neuropsychologist who evaluated my son has a very similar background. She did not interact with him outside of the testing situation, so didn't have the sorts of observations, over time, you describe here.
After testing, she told me that an ASD diagnosis for him was not obvious in his case and she needed to look at all of the data she'd collected to determine exactly what was going on with him.
Her testing included:
Developmental interview with me
Open ended questions to DS' teachers, where they described strengths and areas of concern.
WISC-V
BRIEF (executive function)
ABAS-2 (behavioral)
BASC-2 (behavioral)
MASC (anxiety)
CDI (depression)
ADOS (autism spectrum)
In reading her report, I'd say the most important piece of this diagnostic puzzle was the ADOS, and the other data supported the conclusion.
I'm no expert by any means, and am sharing in hopes it's helpful to you in figuring out what to do to help your DS. I think the neurological angle is really important and the formal testing helps to tease out patterns to aid in understanding.
When my DS was younger, he had a psychological evaluation that in retrospect describes a lot of ASD behaviors, but through a different lens. In that evaluation, the diagnosis was generalized anxiety. Later, a neurologist diagnosed ADHD (but with limited data--rating scales only). It would have been very helpful to have the neuropsychological testing much earlier. I feel like all these years, I've been like the blind men and the elephant: having parts of understanding but without a complete, holistic understanding.
I think there are myriad reasons your DS could be having difficulties in the areas you describe and solid data could help you understand and support him better. So, in answer to your question about a second opinion: yes, I would seek one. It may be a long time before you have everything you need to understand, but since the kindergarten teacher is concerned already--I'd want to pursue more information.
