When Vanessa Lachey got pregnant shortly after her 2011 wedding to Nick Lachey, she was filled with self-doubt.
"Honestly, it didn't really come up until we had our first baby," the Life From Scratch author, 41, tells PEOPLE in its latest cover story about realizing she was still struggling with emotional wounds stemming from her painful childhood. "I said [to Nick], 'If the first one is a girl, I'm going to be terrified.' "
Born in the Philippines, Vanessa moved frequently around the States with her American dad, Vincent Minnillo, who served in the U.S. Air Force, and her Phillippines-born mom, Helen Bondoc, until they separated when she was 3.
Vanessa and her older brother lived briefly in Turkey with Helen and her new husband, who also served in the military, but they were evacuated back to America for safety when the Gulf War began in 1990.
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Helen dropped off her children at Vanessa's father's L.A. home, telling their stepmom she would be back, Vanessa recalls. Over the next several weeks, Helen visited a handful of times but then disappeared.
"Before we were married, we had very deep conversations about everything in life — about our past, about our present situations, and about our future and what we wanted," says Vanessa. "It was really important for me to explain to him where I came from."
The NCIS: Hawai'i star — who's now mom to sons Camden, 9, Phoenix, 4, and daughter Brooklyn, 6 — says she felt fully "accepted" by her husband, but her insecurities came to the surface during their first few months of marriage.
Jeff Lipsky/four.eleven.agency Vanessa and Nick Lachey
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"Nine years ago, I was terrified that I would mess her up, so to speak — that I would fall into these patterns subconsciously," she says. "What I realized nine years later, having a boy and a girl and a boy, is that you don't have to fall into those patterns. And I didn't."
Still, her pregnancy with Camden was an emotional time. While she was thrilled to be growing her own family, Vanessa struggled with "irrational" thoughts, she says.
"Nick and I got married in July 2011 and I got pregnant that December," she recalls. "I was like, 'If this is a little girl, and it's everything he's ever wanted, what if he loves her more than me?' "
Giving birth to Camden first "was the blessing that I needed," she adds. "By the time we got to my daughter, I was ready."
Today, Vanessa can't imagine her life without her three children — and she takes pride in the special bond she shares with Brooklyn.
Jeff Lipsky/four.eleven.agency Vanessa and Nick with Camden, Brooklyn and Phoenix
"She's super intuitive, very smart and very sweet. To see my little girl, I couldn't be more grateful and thankful that I was given her and that I get to be her mommy," she says of her daughter. "They all have these wonderful personality traits, and I love watching them grow and look up to me."
As she continues healing from her past, Vanessa says it's also moved her to see Nick be the "best daddy" to their little girl.
"If I could intertwine my finger with my arm and my eyes and my legs, that's what they're like," she says. "They are thick as thieves, and I couldn't be more proud. Her relationship with her dad is going to be the relationship that I believe defines her as a woman."
For more on how Vanessa Lachey found true happiness with Nick and their three kids after a difficult childhood, pick up the latest issue of PEOPLE, on newsstands Friday.