I think about the past often. It just doesn't seem real. Maybe it's because of my mental illness, since I have trouble remembering what's real and what's not sometimes. But that's rare with me. Anyway, you're the real you. You probably changed as the years went by. Maybe after dealing with mental health issues. It happens to everyone. But that still makes you who you are. The best thing to do now is to focus on what the problems are and then try to find the answers to them. It won't be easy, and the journey might take a long time, but you'll recover and you'll be fine.
Good luck with everything.