First of all, I would like to give u a big hugs. Must have not been easy on you as she had broke your heart.
I came from a single parent family. My family was poor. Really really poor. We survived with the assistance from the govt. My mother slogged 16 hours everyday to raise me up. It was rotating shift. Meaning I don't see her most of the time.
She couldn't afford day care for me. Since primary 4, I have been left alone at home. Managing my homework, cook and wash the clothes.
I could still remember very clearly that I stole $0.20 from my mother just because everyone in the class have a "flag" eraser to play with except me.
And of cos. My mother realized her only coin left on the table was gone and started questioning me. I admitted that I stole. She broke down. She started talking to me in a very adult manner. Bear in mind I was only 10 years old back than. She taught me that we have to be upright. Being poor doesn't mean we are poor mannered or have no pride.
Looking back. The reason why I stole wasn't really because I wanted that eraser so badly to play with the eraser flipping game. It was out of my inferiority and low self esteem at that time. I felt I couldn't blend in with those "friends" if I didn't have that eraser.
You might want to have a heart to heart talk with your girl. She didn't look like its her fault, it could be because she feel like she will "lose face" if she admitted her mistake as she is at the age of being rebellious? Deep down she could have already known that it is incorrect to steal. She could be just lonely. I been through that phrase. It is also not easy on her.
You are her mother. You knows what is best for her more than anyone else. Try an error with different parenting method. I am sure you can work this out with your girl. Don't be disheartened!