Honestly don't have much more experience than you concerning this disorder but from what you describe, he seems to be a HG+ three year old meaning a whole load of wonderful and confusion to his parents! but then again I am no expert and if it's worrying you, I say go find the answer!
I have a similar tyke who just turned 3 who just underwent an evaluation because of his behaviour at daycare (Interacted with the teachers only if he actually needed something, no interest in other children because "they don't like numbers and learning about Mercury", obsessive play with water, extremely active and thus extremely exhausting but could stop in his tracks at the sound of any type of music and get lost in it, terribly defiant, clumsy walking, poor at drawing (although can draw a detailed man on command, eyebrows and all), no interest AT ALL in puzzles EVER and often lapsing into babytalk mixing French and English to the point they thought he was delayed (which was the polar opposite at home where his perfect use of grammar and vocabulary floors us much of the time). They used to say he fluttered like a butterfly from one activity to another, never really settling down etc etc the list goes on and on.
However, this is also the same kid who goes to three museums every week in one day because one wasn't enough (he started to go weekly at 18 months old at his request), going through each display totally hyperfocused and never missing a detail and has a scary memory. Has meltdowns if sounds are off-key or too loud to his taste. Obsessed with order yet can mess up a room in three seconds flat. Psychorigid to the point, that when we go for a walk my husband and I each have to take a specific place at his side otherwise he refuses to move. Doesn't give a rat's bottom if he gets reprimanded or punished but rather tries to deflect our anger by asking us immediately "are you angry?, nah don't be angry, it's not good to shout, shhhh, be happyyyy!" (it's totally infuriating btw
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We thought ADHD and/or autism spectrum. We worried and worried some more. We were saddened he never got invited on playdates or birthdays even though he had known these kids for most of his life. Adults loved him, kids thought he was not particularly pleasant to hang out with. He was an enigma and still is, so we decided to get him evaluated a second time (first was at 13 months upon our pediatrician's advice)
So he went through 4 sessions with a terrific psychiatrist and psychologist and we got this: most likely HG to PG but with no interpretable score on the WPSII (refused to answer the easier questions and kept rolling his eyes with boredom and staring to trash the eval room but perfectly scored on the more advanced ones beaming with pride)with Asperger-like traits due to his precocity but did not qualify for a autism spectrum diagnosis.
They also told us that ADHD diagnosis is most accurate at 5-6 years old but as his hyperactivity was linked to boredom more than constant, it was unlikely.
All of this to say, that getting an evaluation helped us relax and regroup and get support for our decisions. With the psychiatrist's ok, we took him out of daycare which he is super happy about and are now organising a support system in the new daycare we found and outside with a psychologist and ergotherapist. We are also moving in with my parents who have a lot of time to take care of him. We are less obsessed with trying to understand our little enigma's behaviour but more involved in trying things out on a day-to-day basis.Finally we can breathe a little even though lack of sleep still sucks. He told me he was happy for the first time last week.
So for us a psych eval, helped us help him better and certainly stress less. My advice would be if an eval will help you change his life for the better, go for it. Otherwise I'd say, continue to watch him closely and be the amazing mom you sound like you are.
Best regards,
Max's mom
