I don't have much time to go into detail at the moment, but fwiw our youngest dd (8 years old, 2nd grade) has a significant weakness in her associative memory. We didn't recognize it as that until educational testing, which we took her in for because we suspected she had dyslexia - she struggled tremendously to learn to read, and she is extremely challenged with spelling. Different challenge than you've seen in your life, but similar in that her symptoms seemed to fit a common LD but were in fact related to a deficit in memory skills.
She hasn't been through neuropsych testing at this point, and we're just starting down the journey of trying to figure out how to cope with it all. She has an extensive list of accommodation suggestions from the person who did her ability/achievement testing. Did the person who did your testing have any suggestions for coping with the memory issues you have? DD's accommodation suggestions are very similar to common accommodations for dyslexia, but the type of instruction that would benefit dyslexics would not help her, she needs a different type of instruction. Like you, her achievement scores are sky high (but in math) even though her IQ overall isn't as sky high as her achievement.
Re your IQ score, it's really important (if you can) to try to get the subtest scores - an average of "100" could mean all your subtest scores are right around the middle average or.... it might mean you have some very very low and some very very high. This is the case with our dd - the skills that match up with math ability are very very high as are a few others, but the subtest that relies on associative memory is very very low.
polarbear