I really love this. The character design is great and your CGing keeps getting better and better. You should be really proud of yourself for being as good as you are at your age. (I can't wait to see how you'll be in a few years). But I guess I better give some criticism, or else it kinda defeats the purpose of a critique.

- I think you may want to make your lineart cleaner. Even when zoomed out, you can tell that it's messy in some areas, especially around the legs. I think if you drew faster strokes and used the eraser to remove the jagged edges that it would look nicer.

- I really like the softness of the coloring, but I think you should add a some more shading on the dress and pants. Also, maybe you could start coloring your lineart?

- There's a bit too much empty space. I think you should crop it a bit more.

- The hair could use some more shading, too, and some highlights (hair is one of the hardest things to CG for me ).

That's really all I can think of... sorry, I'm not the best at critiquing! Just keep practicing and practicing, and remember to draw things like fruit to help with color theory (and other things), draw nekkid people to help with anatomy, and watch other people draw. In fact, I think you should join drawr.com - even though it's Japanese, making an account is simple and you can watch each image being drawn. It's helped me, at least.

Anyway, great work!