It's a nice piece, easy to see why people have commented on its cinematic potential. In real life the opening harp would be a lot quieter but that doesn't matter here. The harmonic flow is interesting, engaging, and I love the strings during the woodwind figuration - sounds as if the violins are doubling the cellos at 2 octaves and briefly 3 at some point (unless my ears are deceiving me). That gives it an ethereal quality but perhaps should be a little louder. Also to mention the way you gradually bring in the instruments toward the end to build up the density.
Well, if you're working without too much theory, you're a natural for orchestration. Your intuition has served you well. The spacing between the lines is very well worked out - a large space between the bass and the next line up and so on. Your piece has a clarity about its mood.
Very well done.