It's a teen book. Its about 2 girls who are growing up and they don't like it. One girl moves to the big city while the other girl is left alone feeling jealous and upset. Then her dog (I remember the dogs name it was Nora) the dog dies. And the girls go to the big city together and buy dresses and learn a lot of things about being grown up and that its not so bad. I really want this book for my daughter but I can't for the life of me remember the name!

Thanks :)

Thank you anyway everyone, I found out the answer. It's the Trouble with Thirteen.