By InStyle Staff
Updated Feb 25, 2015 @ 1:45 pm
Credit: Courtesy of PEOPLE

Below is an excerpt from “Kelly Clarkson on Her Daughter River: Motherhood Has Changed My World,” which appears in this week's issue of PEOPLE, out this Friday.

Kelly Clarkson never thought her life would look like this. Within a year, she became a wife and a mother of three and couldn't be happier about it.

"My whole life took a big 180,” the singer—who releases Piece by Piece, her first non-holiday album since 2011, on March 3—tells PEOPLE in this week's cover story. "I never thought I was going to be a mom, so it's very much changed my world in the most awesome way."

These days, her life with husband Brandon Blackstock, 38, their daughter River Rose, 8 months, and her stepkids Savannah, 13, and Seth, 8, is a blissful, chaotic mix of homework, diapers, and date nights. And while she still makes time for the globetrotting duties of a pop star, her perspective has shifted.

"I love what I do, but I feel like I relied on my career a lot for my self-worth. And now I'm more than that," says Clarkson, 32, during the revealing interview at her Nashville-area home. "I'm a mother and a wife and have this whole other thing going on."

Since giving birth to River—who Clarkson calls "the happiest baby on the planet"—the singer has felt an unexpected emotion.

"I have a certain level of peace I didn't know was going to come with it," she says. And within her new life, which helped heal some of the wounds caused by her own parents' divorce, she has found a renewed purpose.

"My best friend always says, 'You just want to create the family you never had.' I might be doing that," Clarkson adds. "In defense of my family, it happens. People fall out of love, and people go separate ways. People are human. I've accomplished a lot, but I guess the biggest success I want is that whenever I die people will say, 'She was so successful as a mother, and as a wife.' That's kind of my big goal."

For more of PEOPLE's exclusive interview with Clarkson, including more personal family photos, pick up the latest issue of the magazine, on newsstands Friday.