Stormiand her adorable cousins are growing up so fast!

To celebrate sisterKylie Jenner’s daughter turning 3 years old on Monday,Kim Kardashian Westshared a sweet tribute on Instagram alongside a gallery of photos showing her own daughterChicago, whoturned 3 last month, beside nieces Stormi,Dream, 4, andTrue, 2½.

“Happy Birthday Stormi!!!! OMG Stormi ⛈ You are the smartest, sweetest, silliest girl I know! I can’t believe you are three years old!” wrote Kardashian West, 40, in the caption. “Our babies are so big! Happy Birthday angel girl!”

In the photos, the cousins sit beside each other in different colored outfits. Kardashian West shares Chicago with husbandKanye West; Jenner shares Stormi withTravis Scott;Rob Kardashianshares daughter Dream with exBlac Chyna; andKhloé Kardashianshares daughter True withTristan Thompson.

A source tells PEOPLE that the family traveled to Turks and Caicos to mark Stormi’s birthday,celebrating over the weekendwith more festivities to follow.

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Dream Kardashian, Stormi Webster, Chicago West and True Thompson.

storm’s birthday

“They stayed in a beach villa, had fun with the kids and just enjoyed the sun,” says the source. “They kicked off Stormi’s birthday with a smaller celebration. They also celebrated this weekend and will continue the birthday fun today.”

“Kylie can’t believe that Stormi is already 3,” the source adds. “She couldn’t be prouder of her. Stormi is adorable. She is very smart, very sweet and a lot of fun to be around. Kylie loves her more than anything.”

kylie jenner/instagram

stormi’s birthday

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Last month, Kardashian West got nostalgic on Instagram, sharing a throwbackphoto of herself with Chicago and Stormias infants.

“OMG found this pic in my phone and our babies are so tiny and cute and chunky and perfect!!!” shecaptioned the post.

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ForChicago’s Jan. 15 birthday, the mom — who also shares North, 7, Saint, 5, and Psalm, 20 months, with West, 43 — called her girl “My Chi Chi princess” on Instagram,sharing a recent snapshot.

“You have the sweetest little high voice that I could listen to all day! You bring so much magic into all of our lives,” she wrote. “My heart is so full that you chose me to be your mommy.”

source: people.com