Hello bguimaraes,
I know the feeling and it was the same for me, I was terrified to turn 20, I felt I was entering adulthood and it scared the hell out of me, but quickly withing a month nothing changed, I still felt the same and felt in my head that I was younger. Also the 20's where the best period of my life, getting my diploma in films studies, getting my first job, got my first professional short film made, travelled a lot, and simply didn't care about anything, and it was also in my 20's (at 22) that I got diagnose with Asperger's.
Today at 33, I still don't feel like an adult, in my head and the way I live I'm still in my early twenties, when most of my friends (all NT's) are thinking about settling down, having kids and making plans, me, I just want to continue to travel, watch has much movies I like, collect action figures and continue creating new stuff.
So what I'm saying age is just a number in an ID card, your real age is something else.
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Beauty will save the world -- Fyodor Dostoevsky