YA fantasy book from childhood

So as a kid i went to the library a lot and I remember this book i never finished but only one particular scene. Its killing me that i cant remember or re read it.
Its a YA fantasy book about about a girl who inherited magic from her mother ( i think her mother died ) and the scene i have glued to my memory is she's in a cave dungeon trying to help this boy escape. They run into a what they think is a dragon and the girl gets so scared she pees herself in fright and does a little monologue about it. ( i got second hand embarrassment and stopped reading but now i wanna know what happened.)

wish public libraries kept a log of all the books you read ever incase you wanted to go back to it.

The Shamer’s Daughter by Lene Kaaberbøl.