I don't particularly remember twelve very well, compared to other ages. I can remember eight pretty well, and thirteen, and all the ones after that, but 12 - it would have been 1999 for me; and I think it would have been during a change of school.
I do not remember what advice I could have benefitted from at that age, and its a funny thing to think about how disempowered I would be at a twelve year old, trying to receive advise from my current self.
Funny how memory works.
I enjoyed reading on your "go do Art, and go do Piano" bits. I went and did Art (at university, none the less!), but only started the Piano 18 months ago, and I haven't been regularly playing the Piano in about a year now. It might be time to move some things on :)