The Wide-Awake Princess by E.D. Baker

In this story Princess Annabelle, or better known as Annie, grows up in a family that doesn't enjoy being around her because of a fairy "gift" received when she was a baby. With this gift though, she is able to resist a curse brought upon her sister, and the castle. She then escapes and goes to find Prince Digby, her sister's "true love", to reverse the curse. Joined by Liam, her father's guard, she manages to track down a group of princes and the two fairies she needs help from. From escaping the castle, fighting off beasts, discovering secrets good and bad, and some backfiring magic, Annie is able to save her sister (by finding her true love) and discover her own true love.