I hope you are OK.

You have some very helpful and insightful comments in this thread.

Don't judge yourself based on what you know now.
You cannot expect yourself back then, to have done what you would do now, because now you know a lot more. You have that experience behind you, and you have learned from it.
It would be like looking back to, say, when you first had a driving lesson, and looking back on it after passing the test, and saying, "I shouldn't have stalled the car in that first lesson."

Life is a whole series of learning experiences, and most of these need repetitions for us to really understand them, because life is complex and confusing, so please do not judge yourself harshly from a place where you have the advantage of hindsight.

I too wish I had done some things differently before my parents died, but I must admit that I didn't know then what I know now, so I probably wouldn't have got as much from it then, as I would if I had the chance now. That is an important realisation for me.