Welcome to the forum!
I'm not Type 1 so this is an interim comment while someone else comes along. You say you have always looked after yourself, and if that means having kept a very close balance between insulin and carb intake and all the other things involved in Type 1, then it stands to reason you may well have protected yourself successfully from many complications. Your DB may also have been picked up early and treated properly. And you might be right about having a genetic something that helps! Our bodies are all different and react differently. I guess it's been a complex of factors - but I bet you're glad it isn't going downhill at the moment. Some of that is undoubtedly down to your own efforts so be pleased.
As I say, someone will come along soon who has type 1 and knows more. I just wanted to acknowledge your post.
DG