11/18/2008 at 01:00 PM EST
might be a supermom, but there was one thing she struggled with – breast feeding her twins at the same time!
"It's very hard," the actress confessed on Britain's morning show GMTV.
"I stopped at three months, [it was] about as much as I could do."
The actress, 33, who was in London promoting her film The Changeling
with her partner Brad Pitt
in tow and their four-month-old twins, Knox Léon and Vivienne Marcheline, said she even resorted to manuals on the subject.
"There's this football hold – it's a lot harder than it looks in the books,” she says in the prerecorded interview at her London hotel on Monday. "I did that a few times. I would take turns. It just takes a long time."
The mom of six also revealed that it was while filming The Changeling
that she became pregnant with the twins: "We decided to start trying in the beginning, and by the end I was."
In the film, Jolie plays a mother whose son goes missing, based on a true story.
On whether marriage is important, Jolie says categorically "it's not" – explaining, "we jumped into being a family first. And that just seems like the biggest commitment you can possibly make. It doesn't feel like anything's lacking."
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