When my heart joins the thousand / A.J. Steiger.

Enhanced descriptions from Syndetics:

A heartbreaking debut YA romance featuring a neuroatypical girl with a tragic history and the chronically ill boy trying to break the vault encasing her heart.

Alvie Fitz doesn't fit in, and she doesn't care. She's spent years swallowing meds and bad advice from doctors and social workers. Adjust, adapt. Pretend to be normal. It sounds so easy.

If she can make it to her eighteenth birthday without any major mishaps, she'll be legally emancipated. Free. But if she fails, she'll become a ward of the state and be sent back to the group home.

All she wants is to be left alone to spend time with her friend, Chance, the one-winged hawk at the zoo where she works. She can bide her time with him until her emancipation. Humans are overrated anyway.

Then she meets Stanley, a boy who might be even stranger than she is--a boy who walks with a cane, who turns up every day with a new injury, whose body seems as fragile as glass. Without even meaning to, she finds herself getting close to him. But Alvie remembers what happened to the last person she truly cared about.

Her past stalks her with every step, and it has sharp teeth. But if she can find the strength to face the enemy inside her, maybe she'll have a chance at happiness after all.