EXCLUSIVE OUTTAKES: Nicole & Joel's Baby Album
"I don't even remember what life was like before her," new mom Nicole Richie, 26, says of daughter Harlow Winter Kate, born Jan. 11. "She gives life a whole new meaning and a whole new purpose."
While the parents initially differed over their daughter's name – "I wanted a hippie name and he wanted a more Biblical name," Richie says – the uniqueness of Harlow stuck. "Harlow's a cool name because it feels like a classic name," Madden says, citing the actress Jean Harlow and model Shalom Harlow as two major inspirations.
Attuned to her daughter's needs, Richie says she knows how to pacify her when she's in need. "I'm with her all the time ... I know when something's wrong," she explains. And to soothe Harlow, Richie and Joel Madden, 28, play her lullaby versions of Radiohead and Nirvana songs.
Calling parenthood "the best thing that's ever happened to us," Joel Madden tells PEOPLE that Harlow has changed his and Nicole Richie's life: "We have a very mellow life compared to two years ago, but we wouldn't have it any other way."
"I cried right away," Richie says of seeing Harlow for the first time. "I was holding her, and it was something that was so much bigger than me. Now she looks a little more like Joel, but when she was born, it looked like Joel had nothing to do with it."
"I was watching her in her crib," says Richie. "And she happened to wake up and I was like, 'Good morning!'' And she smiled and it was the cutest thing ever."
"She's never out of my mind," says Richie. "I stop doing things for me anymore. Everything is for her."