When Angie Foy gave birth to her third child in 2015, she knew immediately that something was wrong.

“Our lives changed dramatically when she was born. They told my husband to put his camera down and the (delivery) room went completely silent. I could tell by the look on his face and the doctor’s face that they were in a state of turmoil, like something was going on,” Angie, 48, tells PEOPLE exclusively. “They had no idea what was wrong with her.”

Harper Ly Foy was born with harlequin ichthyosis, a rare genetic skin disorder in which the skin is covered with thick plates that crack and split, according to the National Organization for Rare Disorders.

“Her skin builds up and she loses skin 10 times faster than we do. So in the womb, for eight months, all that skin built up and it became a really thick, white body armor that was really hard. Her eyes were rolled inside out. I mean, she looked different,” says Angie, who lives in Edmonds, Washington, with her husband, Kevin, Harper and their two older children.

After photographs of newborn Harper were sent to Seattle Children’s Hospital, a dermatologist on the Ichthyosis Committee recognized the disease and Harper was flown by helicopter to the hospital, where she spent the next three months.

“Every day she fought for her life,” says Angie. “She shouldn’t have survived.”

The first few months of Harper’s life were an “overwhelming whirlwind,” says Angie, who was unable to hold or breastfeed her daughter. Because the plaque on Harper’s skin was so thick, her circulation was restricted and she was at risk of losing all four limbs.

Harper’s father was the one who suggested that doctors cut open the plaque to allow Harper’s limbs to breathe. The procedure was successful, but Harper also lost the fingertips of her left hand.

“But you know what? She still does everything. Nothing stops her. She plays basketball, she plays soccer, she plays flag football, she models, she dances, she does everything,” Angie says of Harper, now eight.

Still, Harper’s condition requires significant lifestyle changes, including hours of bathing, tubs of Aquaphor, and a large amount of disposable clothing.

“She makes me so proud. I feel like we’ve come a long way. The first few years were really, really hard to navigate this new life and it was challenging, but now we have a really good plan and routine with her,” says Angie. “We shower her three times a day for an hour, so she’s in the water a lot, but that’s to keep her skin hydrated and comfortable.”

Angie describes Harper’s skin as an “open wound” that is prone to infection because her body lacks a certain protein.

“Our program is very strict, but I’m just glad that she’s such a strong-willed little girl despite everything she has to endure every day. It’s hard on her. It hurts, especially when I touch her scalp with all that debris. But she’s still happy, and she’s still Harper, and she’s the life of the party,” says Angie.

Because Harper’s main concern is to feel good and avoid infections, her skin needs to stay moist. That’s why Angie also rubs Aquaphor on Harper. The 8-year-old needs so much Vaseline that she uses a 400 ml jar every two days.

“It ruins their clothes,” says Angie. “It’s not like a normal kid who can just wear their clothes all day and be fine. I spend hundreds of dollars a month on clothes because of all the little things – the underwear, the tank tops, the socks – that I put on first after the Aquaphor and just soak up the liquid.”

Angie estimates that replacing Harper’s clothes, along with the family’s high water bill due to Harper’s bathing habits, totals thousands of dollars per month.

“Having a child with special needs is very expensive,” says Angie, “but I try never to think about the negative because if that were the case, we would be unhappy and she wouldn’t have the attitude, the poise, the guts or the happiness that she has.”

Harper tells PEOPLE that one of her favorite things to do when she’s not hanging out with her siblings Sam, 25, and Jaxon, 14, or in gym class during school hours is “going shopping with mom and eating chicken nuggets.”

In September, Harper will travel to New York City for Fashion Week, where she will model for Runway of Dreams at the 10th Anniversary of Fashion Revolution.

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“She’s walking the runway. I’m so happy for her. I’m trying to use our platform to raise awareness (and show) that beauty is more than skin deep,” Angie says. “I just want everyone to know that she’s just like any other kid.”