At the age you are now, that level of art is actually impressive. Carbon is right as art students have years od practice. I am a model maker (4 years experience) and i'm in a special effects course where people in my year have been doing it muck longer and are ridiculously talented. I don't compare myself to them because I know the difference and I cam to the course to learn. You should do the same and concentrate on improving your own skills. Maybe play with a few art styles and maybe do some free requests to get some good experience under your belt. Do not give up as you my friend have so much potential.