Yes, good to be in touch. I am retired with the time to indulge in correspondence but please don't let me impose on you if your time is much more limited!
I know nothing of health services and health insurance in Germany, but as a Brit ex-patriot in Japan I am familiar with the U.K. National Health Service and the Japanese system. Quite different, and each with their own distinctive advantages and disadvantages, The major one here is that there are no "general practitioners" in Japan. All doctors have qualified in one or more specialities, so every clinic and surgery has its own claimed expertise. This means that each patient has to decide which speciality is likely to be able to correctly diagnose his or her complaint. Since all specialists tend to see thing through their own professional spectacles, this can mean at best a series of fruitless diagnoses until the right one is made or at worst useless treatment for a misdiagnosed condition. As the usual insurance coverage (to age 70) is 70% of the total cost (I.e., you pay 30%), this can be time-consuming and expensive. At my age the burden shrinks to 10% but some procedures and treatments are not covered at all. But given the right diagnosis, the quality of treatment is superb, and usually takes place at a large teaching hospital. I am fortunate in that the doctor who takes my annual proctoscopes is a famous specialist with contacts throughout the profession, and has referred me to highly qualified specialists in each of the areas where my health has suffered. Old age does not come alone, so there have been quite a few (wry grin). The NHS is essentially free, certainly to people of my age, but I understand that it can take months to obtain a consultation with a specialist... I gather that your thyroid problem imposes the same kind of diet restrictions that I saw in my Scots friend. I sympathise! I know it must require an iron will! I love wine more than is good for me, and it takes all my willpower to keep to the one large glass a day on only five days a week, that is claimed to be the healthy upper limit. Mika and I are just back from France, where we cruised the Garonne and Dordogne around Bordeaux and well exceeded our healthy maximum... so we are currently enduring a wineless week to bring back down the averages.