Crown of Feathers by Nicki Pau Preto

In a world ruled by fierce warrior queens, a grand empire was built upon the backs of Phoenix Riders—legendary heroes who soared through the sky on wings of fire—until a war between two sisters ripped it all apart. Sixteen years later, Veronyka is a war orphan who dreams of becoming a Phoenix Rider from the stories of old. After a shocking betrayal from her controlling sister, Veronyka strikes out alone to find the Riders—even if that means disguising herself as a boy to join their ranks. Just as Veronyka finally feels like she belongs, her sister turns up and reveals… Read more.