You are who you have always been at all your "ages".

I'm 57 and can identify with what you say but also can say that at 57 I'm a lot more comfortable than I was at 18 and if I could go back to my 18 year old self with one message, it would be: "It will be okay." (not necessarily great, just okay :-) I don't have all the stresses I did as a young person, all the needs to prove myself, get a good job, start a family, be loved, etc. I managed to get those "tasks" done well and here I am. Ta Da!

It will be okay, lil bit!