Your doctor was incorrect and the dietitian is following the current medical nutrition therapy for hypoglycemia. She needs to find a baseline amount of carbohydrate that will produce no or infrequent symptoms while providing you with the nutrients you need to meet your Recommended Dietary Allowances. Since hypoglycemia symptoms are in response to food, you should be able to stabilize your blood sugar by regulating your carbohydrate intake.
It appears that your dietitian is concerned about the glycemic index of carbohydrates as well. The glycemic index is a list of how certain carbohydrates affect blood glucose. Those with a high glycemic index cause a greater rise in blood sugar. Those foods with a low glycemic index have a low rise in blood sugar. Ask your dietitian about a glycemic index for foods.
Low blood sugar reactions are hard on a fetus’s brain, as that is the organ that uses the most amount of glucose. I don’t have any current references regarding stabilizing hypoglycemia during pregnancy, but doesn’t it make sense that you follow a healthy diet to develop a healthy baby? It is a good idea to get your hypoglycemia under control, but I would discuss getting pregnant with active hypoglycemia with your gynecologist. For some women, the hormones of pregnancy can increase blood sugar levels above normal to the point that some people with normal glucose metabolism become diabetic during pregnancy.
Because of limiting carbs, you may feel like you have few choices, but as your symptoms stabilize, your carbohydrate will be increased to the point where you start having more episodes of low blood sugar. At that point is the threshold of carbohydrate that your body can tolerate without having low blood sugar reactions.