Lisa,
First I want to give you a huge cyber hug b/c you need it. {{{{{{{{{{{HUG}}}}}}}}}}}}}}}} Every parent has self doubt it is par for the course and since your course took you into some unusual areas and methods it is just that much easier to doubt yourself.
I am going to guess that the worse thing you could have done for your daughter is to leave her in that school environment. She was an exploding bomb and from your description it is almost textbook of highly gifted children in reference to high risk situations.
I do have to admit (and granted it was a long read and this could just be me) that I am confused by the ADHD. It sounded like people suggested this to you in the beginning and it isn't until now that you have the diagnoses... am I right on that? I am just a little confused on that point. If you are still not convinced she has ADHD you might want to look into sensory issues. A lot of gifted children get misdiagnosed with ADHD when in fact they have SI. A site you could look at for some guidance on this is
http://www.sengifted.org/.And I just want to add that there are many paths one can take and the path you took with your daughter sounds like a wonderful experience for her. She could have been in a class learning about culture and social studies in a book for what a few hours a week but instead she really got to experience it and I am sure she was taught on the road just more in line with what we do with the toddlers: learn through play method. Where they are learning but not in a sit down grab your books and memorize this method.
Don't give up hope on her potential. Just consider that now you have data to open eyes and with that you also have a starting point for your advocacy. I know before it was the 'experts' and the 'wise' telling you what needed to be done but you are educating yourself and getting the data together so you will be in control not the other way around. This is not to say advocating will come easy but you will have more confidence in yourself.
