normal blood sugar reading but still having weird symptoms....

I am 31 years old, and have been having crazy symptoms the last few weeks. I get these dizzy spells, where I can't think, get a weird tight feeling around my middle, shaky, blurry vision, and very hungry/thirsty. When I feel like I can get up, I need to eat something right away, and then, get so tired, I usually fall asleep for a few minutes. 15 min later I feel much better. I just went to a nurse prac. and she did testing, that showed everything in the normal range, with blood sugar at 83 (after fasting thru the night). Can that still be low blood sugar, or diabetes? My symptoms are getting more frequent. The only thing she found was I was Vitamin D deficient. Thanks for any sugguestions......