The Forgotten Daughter. The Lost Daughters, #1

Born a daughter into the kingdom of Jinu, Xiuying knows nothing but rejection and betrayal, even as a young child. She is left forgotten and raised by maids while her parents, disgraced by her gender, tell the rest of the kingdom that she's dead, when the only thing she wants is love. And eventually, her father and king, Qianfan, sends her away to an abandoned island. to die. But all hope is not lost.
She meets Hua who, along with the rest of the island villagers, welcome her into their home with open arms, and twelve years later, Xiuying falls in love with a handsome prince, Zhang Wei. Now she finds herself back in royalty, but not without consequences. She gets a letter from her parents, telling her that they want to meet, bringing back all the fears that Xiuying had spent her life trying to dispel.