conditions related to ADD? in addion to or in stead of add?

I have a 12 year old diagnosed with ADD, not the hiper active type at all. She has been considered gifted and above her age many times in academic mesurment tests. However she is emotionally very inmature, In fact she enjoys the company of little kids better than kids her age. Her day dreaming and attention problem gets so bad that she nearly flunk school because of the ammount of asignments she forgets to submit or even make some thimes. She is painfully shy and some times anxious. I worry that this is starting to afect her self esteem. I suspect she may have something else, I mean in adition or instead of ADD. Any sugestions? By the way, we live in San Diego.