Knife Faery Rebels Series, Book 1.

Once upon a time, a fariy is born. She lives in an old oak tree at the bottom of a garden with the rest of the fairy folk. Never has she known a time when life hasn't been hard, with many dangers and much adversity. But when she becomes the Hunter of the group and learns to do battle in the outside world, she comes into contact with the dreaded humans and her adventures really take off...