Curse (Book 1 of the Wexkia trilogy) by Dale Furse

Nell wants to go to University, make friends and have a good time.
But when she learns she isn’t human but an alien who her father has been hiding on Earth from aliens who want to kill her, her whole life changes.
When those aliens find Nell, they mean to capture her but they take her newfound alien aunty instead.
Nell goes against her father’s wishes to stay on Earth. She gathers her newfound cousin and the human boy next door, steals a spaceship, and travels to a far away planet to save her aunty and discover why she is hated and feared by many in the known universe.