YA: main character, a girl, is just going about her daily life when she is told she is a princess of the mythical creature world. It involves gnomes and some type of school dance.

[Dani17]

I read this book sometime from 2011-2013

[Sue]

This? It's the first of a trilogy, and was published in 2012.https://www.amazon.co.uk/Switched-Try...

[Lobstergirl, au gratin]

Dani17, are you still looking for this or did you find it?