My recommendation is to keep talking to her about it in a loving manner. keep reminding her it is natural to look at those things. Even for health reason the doctor sometimes ask us to check so they can be sure there isnt a problem when we get sick.
Here is a book I got for my niece before she became a young lady. I have not gotten a chance to read all of it. But what I did read was good. There are other books by this author too that look interesting. Some on appearance and being a good friend. I dont think it really talks about going to the bathroom but it is worth a shot.
The Lily Series #2: The Body Book (Non-Fiction)By: Nancy Rue
Here it is...a book that has all the "girl stuff" you've been dying to know about. In The Body Book, you get the scoop on everything from puberty and cramps to diet and exercise. Filled with fun magazine-type quizzes and imaginative activities, The Body Book not only offers accurate up-to-date information on personal issues that pre-teen girls experience, but also shares it from a positive biblical perspective. Recommended for ages 8 to 12. A companion book to Lily Robbins, MD.