Glimmerglass by Jenna Black

It's all she's ever wanted to be, but it couldn't be further from her grasp...

Dana Hathaway doesn't know it yet, but she's in big trouble. When her alcoholic mom shows up at her voice recital drunk, again, Dana decides she's had enough and runs away to find her mysterious father in Avalon: the only place on Earth where the regular, everyday world and the captivating, magical world of Faerie intersect. But from the moment Dana sets foot in Avalon, everything goes wrong, for it turns out she isn't just an ordinary teenage girl, she's a Faeriewalker, a rare individual who can travel between both worlds, and the only person who can bring magic into the human world and technology into Faerie.

Dana finds herself tangled up in a cutthroat game of Fae politics. Someone's trying to kill her, and everyone seems to want something from her, from her new-found friends and family to Ethan, the hot Fae guy Dana figures she'll never have a chance with... until she does. Caught between two worlds, Dana isn't sure where she'll ever fit in and who can be trusted, not to mention if her world will ever be normal again.

This book is part of the "Faeriewalker" series.
Here are some other books from this series: