Howdy, first off I'd like to say you shouldn't be too worried about your rating. Art is about constant improvement and you should strive to please yourself first and everyone else second (unless it's like a commission or something). Honestly your idea and composition is pretty decent. Objectively I think you need to work on construction, as you still draw from symbols rather then shapes.
Keep at it, draw from references. Good luck and never let your passion wane over some gratification.