Michelle Williams may be raking in trophies and accolades for her work in My Week With Marilyn, but nothing compares to the pride that comes along with her biggest role to date: Mom to 6-year-old daughter, Matilda.

In fact, Williams, 31, has cleared her schedule of upcoming film projects in order to spend more time at home with her little girl.

"I just want to go back to being a mom for a while," Williams -- who welcomed Matilda with the late Heath Ledger in 2005 -- told E!'s Giuliana Rancic on Sunday's Screen Actors Guild red carpet.

Raising her daughter as a single mom, Williams admitted to GQ that she had hoped to give her a sibling, at least before ex Ledger's 2008 death.

"I really wanted, and I really expected or imagined, that Matilda would have siblings that were close to her age. I wanted that for her. But I couldn't make that happen," Williams explains. "And now that she's 6 that isn't even a possibility anymore. So something that was making me feel impatient, that's been removed. For whatever reason, that's not our luck, or our path."

In the meantime, Williams is anxious to share Ledger's legacy with his daughter, who was just 3 at the time of his death.

"You know, as hard as certain things have been for me, it's been harder thinking about how things will be for her," she has said. "I have a lot of things that she doesn't, and some of what I have I can give to her -- the memories that I have, the objects that I have, the physical reminders that I have, the stories."