I understand your reluctance to have your GB removed, but your symptoms sound very much like gall bladder disease. If it's enlarged, then it's probably inflamed, and not functioning properly anyway. The fact that you reacted with pain/nausea during the hida scan is further proof that the gall bladder may be to blame.
Docs can never be 100% sure if the gall bladder is causing all your digestive problems. I had mine out in '97 which took care of all my right side pain, nausesa, fatigue, and discomfort. However, I still have GERD and IBS, so those conditions cause their own symptoms to deal with. You will probably feel much better if the gall bladder comes out. Yes, there are exceptions, but if your GB has been diagnosed as enlarged, and your docs feel this is causing your problems, you should consider having it removed.
Why continue suffering needlessly?
Good luck and keep us posted,