Mary-Louise Parker dishes on adoption

Actress Mary-Louise Parker has been an adoption advocate since she was a little girl.

“I would daydream about it all the time,” Parker told PEOPLE. “I thought about the fact that there were children who didn’t have anything, and I felt like I could help. It was something that weighed on me.”

In August of 2007, Parker went to Africa with Worldwide Orphans and made Caroline Aberash, whom she calls Ash, part of her family. She was already a single mom with William Atticus, her son with former boyfriend Billy Crudup,

“It was something I did for the world and for my son and then for me,” Parker explained. “And when I say the world, I also mean my daughter. Once I knew her, she became part of that. But it’s hard raising two kids as a single person. It’s a lot of pressure.”

The single mom, who split from actor Jeffery Dean Morgan earlier this year, said that sometimes she would like a helping hand.

“I wish I could give them everything that was a perfect little family paradigm, but I can’t. Honestly, I feel like that doesn’t even exist, or at least I try to tell myself that when I am feeling bad about not providing it,” said Parker.

Another challenge was getting William adjusted to the idea he would be getting a baby sister from halfway around the world.

“I didn’t want to give him too much time to ruminate about it,” said Parker. “I talked to him about adoption and asked him what he thought about it, so he understood what it was all about. Then one day he said out of the blue, ‘Mommy, a brother or sister is something that I don’t have, so I think that we should go to the store and get me a brother or sister.’ ”

A few weeks later, William got the news that he would be getting a baby sister in August. “His response to that was, ‘Is that today August?’ When I said no, he said, ‘Good, because I want to go to the park.’ When the time came to go to Africa, you’ve never seen anyone more excited, never ever.”