Thank you for sharing Marilyn! Even though I’ve only been at this a few years, I have some similar frustrations.
I’ve been diabetic for only six years, have only had two A1cs over 6.0% since diagnosis and rest between 4.6%-5.2%. I did low carb, plant based, keto, etc. Worked out, did all the right things, tested like crazy, started biking/hiking/skiing around town exclusively.
Dropped my body fat to TWELVE PERCENT! at one point while having my A1c at 4.8%. No significant lows in that year (kind of hit this magic combination of diet, exercise, and insulin). I felt like a champion 
And within one year of that, I had a minor bleed in one eye, severe neuropathy in my feet and hands, and a whole bunch of other stuff as well. Turns out I have at least two other autoimmune diseases affecting me in very serious ways, but… I was super disappointed to find out that the retinal bleed(s now) and peripheral neuropathy are almost certainly related to my diabetes.
My neurologist, my ophthalmologist, and endocrinologist all agree that: my diabetes is in great control and has been since diagnosis; and that I have complications anyways (within five-six years). Why? They don’t know, except that some people seem to get complications regardless of control, length of time, etc. They don’t know, and I don’t know either. But they all agree it wasn’t something I did or didn’t do to myself.
So… I still feel like I did something wrong somewhere, and it still feels unfair, and I totally don’t understand it. And I have a PhD in biology and I don’t get it. I do know that I have to keep plugging along, staying in control as best I can, and let my doctors help me as best they can. I’m sorry, and and am sure your vision will clear back up! You are maximizing your chances to live well with this disease, and that’s all any of us can do.
Edit: also, thanks for the reminder: I really need to make an appointment with my ophthalmologist, who I haven’t seen in too long thanks to COVID.