Ashlee Simpson - Simpson-Wentz Wants A 'Big Family'

ASHLEE SIMPSON-WENTZ is eager to expand her brood with rocker husband PETE WENTZ, insisting they both want a "big family".

The singer/actress gave birth to the couple's first child, Bronx, in 2008 and she's leaving it up to nature to determine when she will fall pregnant again.

She tells UsMagazine.com, "We would love to have a big family. (But) you can never plan something like that."

The star admits little Bronx is growing up so fast and she's treasuring witnessing every step in his development.

She says, "Every day is like a milestone, I swear. It is the best thing. I mean, being a mother, taking the time that I have taken off just to be with him has really been incredible. Every day he is learning something new and growing. It is fantastic. I feel very fortunate."