Hi there and welcome. I'm still wading through the 2E world myself but here are a couple of posts you may want to read over.

http://giftedissues.davidsongifted....ret_low_digit_span_score.html#Post103963

and

http://giftedissues.davidsongifted.org/BB/ubbthreads.php/topics/46560/1.html

My son also had WISC scores so scattered that they couldn't really give me a reliable score. His coding was also really low. All over the map. The scatter and low coding can definitely indicate 2E issues. My son is also in Montessori (1st grade) this year and it's been pretty rough for him. He doesn't complete his work, complains about doing it and that it takes too long. Has a poor attitude, etc. So, we applied to the gifted program at the public school for next year and he got in so that is our next step.

Here is a link to my son's results and the advice I got. Since I posted this, we found out that my son has visual processing issues (he had surgery for strabismus) and sensory integration issues. He did not do as well on any subtests that were timed probably because of his eyes not being able to rapidly focus on the questions.

http://giftedissues.davidsongifted....s_are_in_gifted_but_slow.html#Post137242

You may also want to check out a book called Misdiagnosis and Dual Diagnoses of Gifted Children to see if he really has ADHD. Has he been tested for learning disabilities?

Mom to 2 kiddos - DS 9 with SPD and visual processing issues and DD 6 who is NT