Welcome to TGH Selene!
While much of what you described resonates, I have to respectfully disagree with the title of your post. I don’t consider the decades I spent denying my true gender identity to be a waste. I don’t think you should either. Give yourself a break.
There are no prescribed timetables. Each of us has our own path. It takes however long it takes to discover who we are. Some of us simply need more time. The years we spend denying our true identity provide countless data points that ultimately confirm we are on the right path. I am entirely sure this is what I want. I couldn’t have confidently made this decision 10 or 15 years ago.