Wow! You have a very gifted child on your hands- I can't believe the schools haven't recognized this! We had a similar problem with the Cogat - my ds10 took it twice and didn't make the gifted cut. We later had private testing and he scored 140 On WISC. In all of four years of Elem school not one teacher ever mentioned the word or thought of gifted to us- he did have behavior issues though- very high energy. only one student teacher tried to tell me he was gifted- simply because her son was gifted and she said he reminded her of him-so I'd say teachers aren't the best identifiers which makes it very frustrating.
I investigated the Cogat and discovered that he had simply run out of time.
He had a slow and accurate approach where nearly everything attempted was correct he just didn't finish. He is also having similar issues in school now - not finishing math tests. He's proven his ability of higher math when no time constraints, but when there are limitations in time the scores go down.
I am currently working on getting more time for math tests as the tester suggested this in the report.
Good for you for appealing the G&T decision- I did the same thing and got him into G&T, unfortunately it was just a weekly pullout and kind of a disappointment
: (
Good luck!