I had dietary issues and went to a registered dietician/RN nutritionist.
Her information helped me tremendously. If it's possible to consider a nutritionist for assistance, I suggest it.

If you have a specific need, and can find a cultural diet which addresses it, that helps take the sting out of the changes. I have found that for myself eating a lot of Japanese style food, within my understanding of it, has allowed me to eat within my restricted parameters but not feel deprived. A friend chose to eat more of an Indian diet, being more dairy oriented and meatless.

Be careful of the protein powders out there, some of them have strange additives.
If you eat eggs, hard boil a dozen once a week, just to have available to you.

I hope you find a great solution for your system.