Welcome!
No diagnosing over the internet...but I would say the behaviors you report, plus the personal weakness in working memory, do suggest that it may be worthwhile for you to have a professional look at him in person.
Being cognitively PG does not automatically mean having poor executive functions (though EF may look like a relative weakness, especially when age-typical EF is contrasted with well-advanced-for-age cognitive or academic skills). At his age, he should be able to handle more than one-step directions, whether PG or NT. A thoughtful and comprehensive evaluation by a qualified professional (neuropsychologist, clinical psych, experienced school psych) may help you to tease out what is age-appropriate, what is personally discrepant, where it might be coming from, etc. Do look at experience with and sensitivity toward GT kiddos as you are selecting providers. This makes a considerable difference in the usefulness (and sometimes even the accuracy) of the evaluation.
