When I Became A Commoner, They Broke Off Our Engagement! (Manga) Vol 01

Thirteen-year-old Anna was raised in a noble household, yet she looks nothing like the rest of her family and lacks her lineage's aptitude for magic. What she doesn't realize, however, is that a mischievous fairy switched her with another baby at birth! When this detail comes to light, Anna's family kicks her out and ends her longstanding engagement to Edmund, a young nobleman. How will Anna learn to adapt to life as a commoner with her new family? Yen Press
(W) Kenzi Oiwa (A) Kaya Kuramoto, Kaoru Takanashi