"I'm always open to being a better parent," Rehab Addict's Nicole Curtis tells PEOPLE of being a mom to sons Harper, 2½, and Ethan, 19

For Nicole Curtis, her journey toward being a great mom is a flexible one.

The Rehab Addict star told PEOPLE during a recent sit-down for Celeb Parents Get Real that she thinks her best quality as a mother is her willingness to switch up her techniques and always be learning.

“I’m always open to being a better parent,” said Curtis, 41, who is mom to sons Harper, 2½, and Ethan, 19. “There is no ‘I’m the best parent,’ there is no, ‘I’m the parent, you’re right’ — you have to be open to change.”

“You don’t know that going into parenthood, but as soon as you hit those teen years … whatever everyone tells you to do, whatever you think you should do, do the opposite,” she continues. “Because there’s really understanding and growing. There is no rigid lines of parenting. It never works that way.”

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The HGTV star admits that she is “the queen of unsolicited advice,” because she has learned so much over her years of being a mom — and if she could advise a pregnant woman on one thing, it would be to get a doula.

“Instead of registering at some baby store for some baby bouncy, some baby swing, at your baby shower say, ‘I want money for a doula,’ ” she says. “A doula is a caretaker that helps you before birth, after birth — whenever you want.”

Adds Curtis, “They’re also professionals. They know everything about babies, and even an experienced mom like me — they don’t know everything about babies.”

Curtis — who has been candid about her decision to continue to breastfeed Harper and her opinions on other controversial parenting topics, like circumcision — says her nickname might surprise some.

“They call me the kooky, crunchy hippie mom, and I don’t think a lot of people expect that because they see me rough and tough at work,” she says. “But then if you see me on the side, I have my ring sling on, I got the baby on the boob, there’s no makeup, the hair is knotted up.”

“It is a very rare moment if my children see my hair down — they’re wondering where I’m going, what is going on,” adds the mom of two.

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Curtis says her two boys are very social, which comes in handy for making new friends — for both them and their mama.

“We were at the playground the other day, and this mom was there and she had four girls that looked just like my little guy and I was like, ‘I have to be friends with her because they all match!’ ” she recalls. “By the end of the week, she was over at my house and there were four kids in my backyard.”

“That’s really important to me — that my kids know [to] make friends always,” Curtis shares. “You’re never gonna regret having more friends. The more the merrier.”