Yes, I noticed that as well. As I started reading I thought the book should have been in the fiction section. But as I got further into the book, I realized that this couldn't be classified as a historical novel either. The way it is written, some of the entries use dialogue to tell the story, others use the narrative. It really IS written as a journal. So, I suggest you leave it as it is. I really loved the book!
Jennifer, you make a good point. I have been keeping a journal for years, and there is no way it would ever read like a novel.
I bought the book thinking that it was a biography, and discovered upon reading it that it was written in the first person. It makes no difference. The historical facts are well-researched and footnoted, and the book was very enjoyable.
Obviously it is fictional, the author even says so on the web site. Too bad the publisher didn't call it fiction, but every one knows Diane didn't write a journal.
No, she didn't. That's what most of the emails are asking.