Paris Hilton (search) is trying on a new outfit: a hard cover. The model-reality TV star is publishing a 198-page memoir, “Confessions of an Heiress: A Tongue-in-Chic Peek Behind the Pose,” (Fireside).

Though the missing Chihuahua saga was too recent to make the book, Hilton writes about her youth as an heiress in a “really close” family. Excerpts of the book (to hit shelves Sept. 7) are printed in the Sept. 6 issue of People magazine.

“It’s traditional for an heiress to be raised in a sheltered way,” she writes. “No one thinks that’s true of me, but it actually was.”

Still, Hilton insists that she was not coddled: “The rumor is that I got a credit card at age 9, which is ridiculous. It was more like 19, and I had to get one myself without my parents.”

Her “Confessions” reveal a girl not as confident as the runway model frequently seen in the tabloids. “It was so embarrassing being flat-chested that I wore padded bras til I was 17. Now, I’m happy to be small. It looks better in clothes. But back then I was really insecure.”

The notorious party-girl also feels a change coming: “I don’t always want the glamorous, jet-set life. Let’s face it, I’ve done it. Someday soon, I want to have children and a big house with a lot of animals – like my parents had.”