OP I think Mamanyt has it... "YANBU to wish that he paid more attention to what you told him about your health. Not in the least. However, YABU to expect it of him, knowing him as you do."
I am afraid I put YABU because I don;t think remembering things is a sign of care, speaking for my own life. However, I do think sometimes we want more from some family or friends than we ever get!
And I agree with Stichintime "I don't think its not caring, its either being distracted or self absorbed. I find people get more like this as they get older!"
And I would count myself now in my mid to late 50s in the 'older' category. I can't remember what people tell me. Even special people, even important things! If someone says "Did I tell you XYZ...?" I say you probably did but remind me about that again.
I wonder if a bigger issue is that you say "he's not interested in any more contact than that". He's maybe not nearly as involved or caring as you would like, but maybe this is all he can manage.
I am so glad the results were good and in your shoes I would focus on that. People who cannot give you what you need, well it is sad, but wasting energy over it is a waste, focus on people who do care or on people who you can put that care into them.
Both my parents are now dead, in the case of my dad quite long dead. They showed little interest in my school life and at times I felt frustrated but they fed and clothed us, did our washing and drove me around and were there when needed. I look back now and think they did a lot which at the time I did not appreciate. But in later years became wrapped up very much in their own lives.
Hope you stay well. 