The actress, who welcomed daughter Ryan back in May, reveals that motherhood "changes everything about you."
"The thing that's changed the most is how little I miss my life before Ryan. She monopolizes all my thoughts and all my emotions, and I just couldn't be more grateful for her," Duff tells toofab's Rachel Hoffman. "I think the biggest surprise is how little I miss my single-person freedom."
And while younger sister Hilary Duff has more experience with parenting 3-year-old Luca, she doesn't push her advice onto Haylie.
"As a mom, you don't always want advice. Sometimes you get a lot of unsolicited advice," she says with a laugh. "We just try to be there for each other and support each other. If one of us needs something, we go to each other first. We aren't necessarily trying to push our way onto each other, which is really great."
The famous sisters even have sleepovers together with their kiddos!
"We had a sleepover on Friday night with the kids," the proud mom gushes. "Luca is really starting to enjoy showing Ryan his toys and the things he's into. He's really turned a corner with her when I explained that because he's older, he gets to tell her what games to play. He was pretty excited about that. He really is just a special little boy. He's really sweet and I think he's going to be a great big cousin to her."
"It's important to me because I'm a new mom. I know how I feel when I make a mistake or I can't do something that I really wish I could," she says about her reason to get involved. "To consider how other mothers feel when they can't provide diapers to their child, it feels emotional to me. It's something I can about and relate to."
Duff is also about to start shooting the new season of "Real Girl's Kitchen," telling us that she "can't wait to get back in the kitchen with my daughter propped on the kitchen counter."
The 30-year-old star is learning to cook quick, simple meals with very few ingredients. "I just don't have the time to dedicate to being in the kitchen," she explains. "I'm sure as [Ryan] starts to eat real person food and not breast milk, then I'll start to experiment with a few more things. I'll have to come up with recipes that I can feed [fiance Matt Rosenberg] and Ryan at the same time. One will get curried apples and one will get apple pie!"
It seems that Ryan might even inspire her mama to start a baby food line!
"I would love that! I think feeding a baby – and feeding your baby – is so intimate," she declares. "The choices you make are so important. I would love to be able to bring healthy food to babies."