Hi Mr. Bowski!
I was 12 when I read Dashiell Hammett's mysteries. They made me wish to be a writer. I became a mathematician first, and work as a scientist. A dozen years ago, I got serious about writing and after years of hard work, sold a novel that is now in print. Since then, I have sold two more, and also a classical musical composition.
My advice to you at 12:
Be your own best friend.
Read to learn what you like and don't like.
Always believe in your own dreams.
Don't give up on them, or yourself.