Ashley Graham 'Can't Believe How Fast' Her Twins Have Grown as She Celebrates Their First Birthday

Ashley Graham/instagram

Ashley Graham's twins are officially one!

The model celebrated twin boys Malachi and Roman's special day over the weekend, sharing scenes on Instagram Saturday.

Looking back on her journey of tandem nursing the twins as newborns, she wrote, "Missing these moments. I can't believe how fast this year went!!"

The mom of three shared a glimpse at the twins enjoying their big day as she pushed them in a double stroller as they wore matching gray camouflage sweatsuits while she wore a black winter coat and an orange hat.

Later, the little boys could be seen sitting in their highchairs, with their faces just out of frame, as they sat in front of tiny birthday cakes with each of their first initials on them. Roman's cake had white frosting while Malachi's appeared to be chocolate.

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RELATED: Ashley Graham Says She's Appreciative of Her 'New Tummy' Nearly 10 Months After Welcoming Twins

In addition to the twins, Graham, 35, shares son Isaac Menelik Giovanni, 2, with husband Justin Ervin.

Sharing an early scene from the family's Thanksgiving on Instagram in November, Graham captured a moment where twin sons Malachi and Roman and big brother Isaac Menelik Giovanni played together in their nursery.

The boys explored a bin full of toy cars and trucks, with none of their faces visible in the photo. The twins were dressed in shark print pajamas, while Isaac wore a blue hoodie with light brown printed pants.

Speaking with PEOPLE about her work with Bobbie as a founding member of the Bobbie MotherBoard, and her historic new billboard showing her combo-feeding twins that debuted in September, the supermodel mom admitted that the feeding "journey with the twins has been an interesting one."

Ashley Graham/instagram

"I thought that I would easily be able to breastfeed without having to think twice about it. I knew that there was going to be a little bit of actual juggling that would have to be implemented because everybody and their mother told me that if I didn't feed the twins at the same time, I was never going to have any time for myself," she explained. "And sure enough, that's exactly what happened. I had to figure out how to do it at the same time."

Graham shared that she gave herself six months to give tandem breastfeeding the twins a sincere try, making sure to check in with herself "mentally and emotionally."

"The first week was so hard," she admitted. "It was trying to figure out how to do it. They would latch. They would unlatch. I couldn't figure out the positioning."

Graham said she found success for about a week and then "all of a sudden it was like we didn't want to do it anymore, and I felt defeated. I felt like what am I going to do? How am I going to feed my babies?"

Graham said she had to have "some internal conversations with myself" to get through the tough moments.

"I remember telling myself, 'It's okay if you have to use formula. Don't worry. You're not failing as a parent.'"