First I am very glad you live in New York City, I do as well. My daughter, 20, is suffering the same way as you. She is studying at Duke University. We are looking for a doctor for her here or in Durham, NC who will do the Glucose tolerance test by the book. I di not find anyone so far. I am glad to hear that you have found one. If it is not so much trouble could you please send me his/her information.
Also you should read two books that I have posted here several times but will gladly do it again.
1. Hypoglycemia - by Geraldine Saunders and Dr. Harvey Ross.
2. Low Blood Sugar - by Martin L. Budd
Also Austarlia is much more advanced in this area. So see the link below they may have some info' for you. There is a association of Hypoglycemia in Austarlia which you can Google and find out how to contact them.
Good things you are already doing is Yoga, do not do any heavy excercise, don't eat sugars and corn syrup products. Complex carbohydrates are very important in your diet. Are you a vegetarian?