Can a nonverbal learning disorder worsen as time goes by or do more symptoms appear as a child gets older and the schoolwork becomes harder?
Also, she's been dancing for six years and in Girl Scouts for three years. She wants to quit. Would that be a mistake? She is a good dancer and I have seen a remarkable adaptation in her social skills bit by bit over the years.
Many times children with nonverbal learning disorders are misdiagnosed as having ADHD. If ADHD has been "ruled out" by her neurologist, I don't understand why he wants to medicate her.
As for her dancing and Girl Scout participation, I can see how these two activities could really support her growth and social development. Have you talked to her about why she wants to quit? Have you sought out the leaders/teachers of these groups to see if there have been any social conflicts that could have contributed to her reluctance to return? If accommodations could be made in her schedule, perhaps she would agree to return to at least one of these activities on a limited basis. For now, at least, the choice to participate or not has to be hers. Is she interested in trying another activity that would allow her to interact with other students in a non-academic sphere?
If you would like more information about the social/emotional as well as academic needs of children with nonverbal learning disorders, have a look at Sue Thompson's book, The Source for Nonverbal Learning Disorders. She offers a wealth of suggestions for accommodations and supports that might work for your child.