09/06/2012 at 06:00 AM EDT
When she moved to Los Angeles 12 years ago, Pink
was a very different person from who she is today.
"I was a delinquent," the Pennsylvania-born singer-songwriter tells PEOPLE in its new issue. "An angry, rebellious, self-righteous, ambitious, crazy person who liked to have too much fun."
And now? "We have no idea what we did before having Willow," she says of her 15-month-old daughter
with her husband (since 2006
), motocross champ Carey Hart
. "Having a child is the best thing that could happen."
Pink, who turns 33 on Saturday – and performs on Thursday's MTV Video Music Awards
– didn't know what would happen when she returned to the recording studio in January to work on her new album The Truth About Love
, due out Sept. 18.
"Every time I make a new record I'm like, 'I wonder if I can even sing or if I have anything to say,' " she says. "I mean, I've been changing diapers and having dinner parties, who does that? I don't even know who I am!"
It turns out writing was like "turning on a faucet," says the pop star – but just don't expect lullabies about the joys of motherhood. Instead, fans will get more of the playful kiss-off songs the Grammy-winner's fans have grown to love.
After all, says Pink, "I'm still nuts, and I'm still angry!"
For much more on Pink's current life – including how she's tackled the ups and downs of marriage, and how she got her body back after giving birth – pick up this week's PEOPLE, on newsstands Friday