You don't have to do a horse if your still puzzling about that, any animal could be used for the bottom half. A colourful snake would give you lots of energetic coils to add dynamism to your composition for instance, and may take up less space, or a mermaid or something. EDIT sorry, just noticed the unicorn horn on her forehead, might make changing the horse difficult if you wanted to stick with that...
Also (going off an earlier wip here) I would have her looking at where she is firing her arrow, the latest picture of her face has her staring off somewhere else and feels disconnected to me.