As above, seems like you've already consulted endocrinologists re: your thyroid but you must have the Hashimoto's thyroid or another strain to want to speak with an immunologist...
My FrauenArtzt Dr. Summerer-Moustaki (655-386, Shoenstr. 8 right across from
CandidPlatz) has Endocrinology as another sub specialty listed on the American Consulate in Munich website. Perhaps you want to meet with her and see who she would refer you on to?
She is American raised so is a native English speaker.
Good luck. (And don't you need to take Iodine in Europe if you have auto-immune thyroid disorders?)
see also: www.munich.usconsulate.gov