12/06/2007 AT 04:50 PM EST
While her ex Joel Madden preps for a new baby with Nicole Richie
, singer Hilary Duff
is delaying her own plans to start a family.
"I'm definitely not ready to get married," Duff, 20, tells Cosmopolitan
in its January issue. "I think a reason that people in this business get married young is that they feel like everything comes to them sooner in life. It's normal to be like, 'Okay, what's next?' "
Having famously dated Good Charlotte musician Madden for 18 months – before they broke up
in November 2006 – Duff is currently dating
NHL player Mike Comrie.
On the heels of this week's Jennifer Love Hewitt controversy about body image
, Duff said that, as a scrutinized starlet, she has fretted about her weight.
"You lose some happiness when that's all you think about," Duff says. "There definitely was a time, about a year and a half ago, when I was pretty obsessed with my body and my weight, but I'm better not stressing about my body all the time."
She adds, "It's not attractive when girls get super-skinny. Guys don't like it. Girls don't like you as much."
Next year, Duff will be tackling her first serious movie role, in War, Inc.
, costarring John Cusack. This year she spent promoting her latest CD, Dignity
, which hit stores in April.