Pregnant Heather Rae El Moussa on 'Close Relationship' with Stepdaughter Taylor: 'Got So Lucky'

Heather El Moussa/instagram

Heather Rae El Moussa is opening up about the special bond she shares with stepdaughter Taylor.

The pregnant Selling Sunset star, who is currently expecting her first baby with husband Tarek El Moussa, shared a sweet post on Instagram Tuesday about the 12-year-old, expressing her appreciation for the "close relationship" she has with the pre-teen.

"Got so lucky with this one 🤍 I met Tay when she was a little girl and the second I met her, I knew my life was going to change. She melted my heart. She opened her heart to me day one of meeting her," Heather wrote alongside a photo of the pair hugging. "There was never an 'awkward' phase for us."

"Not everyone can understand the close relationship I have with the kids & that's fine, all that matters is how we feel. The kids made me want to have kids, I love my role as their bonus mom❤️."

Along with Taylor, Heather is also stepmom to 7-year-old Brayden. Tarek shares Taylor and Brayden with ex-wife Christina Hall.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

RELATED: Pregnant Heather Rae El Moussa and Tarek El Moussa Tease Possibility of 'Back-to-Back' Babies

The mom-to-be went on to share how "amazing" her stepchildren have been as she prepares to welcome her first baby.

"For anyone who's asked me about how the kids have been throughout my pregnancy: my honest answer is that they've been amazing," she wrote. "Bray checks on me constantly and is so sweet about my belly and Tay couldn't be more excited to have another baby brother."

"She is so caring beyond her years. And told daddy 'if I'm at school and Heather goes into labor call the school right away so I can talk to her & tell her good luck & I love her'🥹," Heather concluded.

Tarek and Heather were in the middle of in vitro fertilization treatments, and had even scheduled a date to transfer an embryo, when they were happily surprised to learn they were expecting, they told PEOPLE exclusively in July.

Heather Rae El Moussa/Instagram

"It was a huge shock," said Heather at the time. "We just weren't expecting this. We had just gone through IVF. We had embryos on ice. We had a plan."

But after the disbelief wore off, the Selling Sunset star was elated. "I think when you least expect it and there's no stress in your life, the world just brought us what was meant to be. I'm so excited that it happened like this."

Speaking with PEOPLE in November about how the family was anticipating their new arrival, Heather said everyone is "getting really excited."

"The nursery is coming together and it's so sweet because we're all calling it 'the baby's room' now, even the kids," she shared. "It's just really cute."