Michelle Williams says "being sexy" is not one of her most distinctive qualities.

The actress stars as Hollywood sex symbol Marilyn Monroe in BAFTA nominated movie My Week With Marilyn but doesn't want to be defined by her sexuality.

The 31-year-old mused that when she was younger she didn't really appreciate her erotic appeal.

"I wouldn't say that that would be one of my first qualities as a human being - being sexy," Michelle told GQ magazine. "It's funny spending your 20s running away from it, and then you hit your 30s wait a second! Come back! I want that time back when I didn't appreciate what I had!"

The mother-of-one also revealed why she no longer feels under pressure to find love.

Michelle dated the late actor Heath Ledger and has a six-year-old daughter, Matilda, by him. The couple broke up before his untimely death, but the blonde beauty hasn't found Mr. Right yet.

The star explained that her wish for another baby used to make her impatient, but nowadays she is more relaxed.

"Because I really wanted, and I really expected or imagined, that Matilda would have siblings that were close to her age," she said. "I wanted that for her. But I couldn't make that happen. And now that she's six 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."

Michelle and Heath met when shooting Brokeback Mountain and they began dating in 2004. She can vividly remember what it was like when they first got together and still finds his passing hard to accept. He died of an accidental prescription drug overdose in 2008.

"Our initial meeting, the circumstances of how we first met, were cosmic or something. Yeah, a lot of things happened at once. It's a bit like: we had a lot of things to do, because we didn't have a lot of time, or something," she said.

"[His death] was making me crazy. I felt like I was going crazy. It was too much - trying to deal with what had happened and trying to deal with what was at our doorstep. I just felt trapped. And it's not just me - there's somebody else who I'm trying to protect [Matilda], and I can't. I can't make it stop, I can't make it go away."