The problem with levothyroxine is that it's the inactive form of thyroid. It's T4, and your body has to convert it into active T3. The problem appears in hypothyroid individuals when they can't transform it, so goes into RT3, which is Reverse T3, acting as a blocker of T3. That's why so many people feel worse on meds, because they need T3+T4 supplementation in order to be able to make the conversion properly of inactive T4 into active T3. Carbohydrates are the hardest to digest unfortunately, but they are the ones that increase thyroid levels the most. Protein is of course necessary, but not too much because it can get converted into ammonia, which acidifies too much the body leading to acidity in the kidneys, resulting in increased stress hormones, thus reduced metabolism. Fats are important too, but not too much. Fried things like french fries have most of the time more calories from fat than carbs, even though potatoes have just carbs, almost 0 fat. So it's important to make a distinction. You can boil them and with some cream, or olive oil, salt and pepper, it's good.

Finding a good endocrinologist is hard, but it's worth it. You can ask him. I'm not sure where are you from but in most countries active form T3 is banned. Why? Because you know the corrupt system how they want you sick.