Dawn Weaver - Soul Flames, #1

An ancient evil stirs in the kingdom of Avaraline, and the fate of all life in a world blessed by magic hangs in the balance. The Guilds and Clans, who hold the power of the lands, are ill equipped to deal with the unknown threat, with corruption spreading through their ranks. Not that this is of any consequence to Izen, a young man struggling to survive in a dying village, and Myne, a talented young Dragon rider seeking to prove herself.
That is until the infamous Witch is sensed near his village and Izen becomes intertwined in world of the Dragon riders. Literally, with the magic awakening in him too. The complication, is that only females can be riders. This is the first book in the Soul Flames series, and is the prequel Soul Flames volume 1. Note that this is a transgender story, and features queer themes.