So B. It — Sarah Weeks

Heidi Is On A Quest
She doesn't know when her birthday is or who her father is. In fact, everything about Heidi and her mentally disabled mother's past is a mystery.

When a strange word in her mother's vocabulary begins to haunt her, Heidi sets out on a cross-country journey in search of the secrets of her past. Far away from home, pieces of her puzzling history come together. But it isn't until she learns to accept not knowing that Heidi truly arrives.