I did consider sending you a PM, but I suppose there's no harm done in expressing this opinion publicly :p
I think the work you have done is absolutely brilliant. Not just considering that you're fifteen years old: your Sun and Moon "Title Screen" is a sheet that, after a few edits, I would pick up and learn; your "Konikoni City" is clean and accurate, even more so than some of my current sheets. And most impressively, the orchestration in "Grand Tale" shows that you've properly thought about the way the instruments in the band work, long before writing - you're thinking about harmonies, rhythm, even timbre. Personally, I don't think I would have been able to write anything that you did at fifteen years old.
But it's not about me, really: I'm just so impressed with what I saw, and a part of me really wants to get to know you and possibly guide you along a little. Of course, it's not perfect, and when new people come to NSM there are formatting and stylistic expectations, so that's why it's timely that you found your way to this community. ^^ When I came back to arranging last year, Latios212, Seb, Braix and a host of awesome people opened up to me on Skype to talk about arranging - what I hope for you is that very soon, you'll find yourself inspired and motivated to keep writing and write better, through this little community here

You
clearly know what's going on in VGM. After doing lots of listening and quite a lot of arrangements, I'm now certain that the challenge of the main Pokemon OSTs is rhythm, and the challenge of the PMD OSTs is melodic layering. These are challenges that need deliberate thinking and creative decisions to overcome: more often than not, you can't just transcribe and pick your parts (past the 3rd Generation, of course xD). From what I've seen so far, you're really getting it.

If you don't mind, in a week or so, I'd like to get in contact with you on Skype or something to talk music - just as the awesome people who helped me when I first came did. ^^ When so much potential just overflows out of someone and you know they've got passion...ooh. That's inspiring.
And of course, with you being a Singaporean, at some point perhaps we could meet up and talk about music things. But that's something I'd presume you'd rather save for the far future xD
~
For now though: hope that this gives you a little bit of confidence to keep at this awesome work you're doing. ^^ I'll be following your thread for sure, but no pressure!

Keep doing what you're doing as long as you enjoy it, can't wait to see what else you can pull off~