'I Am Shauna Rae' Sneak Peek: Shauna Has Trouble Trying on Bridesmaid Dresses — 'Nothing Fits Me'

"It was extremely intimidating shopping in an area that you know nothing is going to fit... it's a mess," Shauna, who stands at 3 feet and 10 inches tall, says in PEOPLE's exclusive clip

Shauna Rae is getting ready to be a bridesmaid.

Shauna was diagnosed with a rare form of brain cancer when she was just 6 months old. Though treatment helped her into remission, it also left her pituitary gland almost dormant and stunted her growth. As a result, Shauna, now 22, stands at 3 feet and 10 inches tall, which is the average size of an 8-year-old.

In PEOPLE's exclusive sneak peek at Tuesday's episode of the TLC series documenting her story, I Am Shauna Rae, Shauna goes bridesmaid dress shopping with her two sisters, Rylee and Tara, and their mom, Patty. However, because of her height, Shauna has a difficult time finding dresses in her size.

"It was extremely intimidating shopping in an area that you know nothing is going to fit," Shauna tells the camera. "But [also] just shopping in general, because it's a mess. Nothing fits me."

After picking out a few gowns, Shauna ventures into the dressing room to try them on. When she comes out wearing the first dress, the gown is — to no one's surprise — far too big on her.

"Okay, this one fits not at all," Shauna says through laughter. "The boobs are too big!"

Referring to the dress' length, Tara also points out: "Everything is too big! It's not just the boobs."

Shauna Rae and her sister Rylee. tlc

"It's like a breastplate," Shauna jokes as she holds the gown against her chest and a bridal consultant ties the back.

"[It's like] some armor!" responds Tara, who usually lives in Florida with her fiancé Jesse.

Shauna then goes back into the dressing room to try on a junior bridesmaid dress — but she has no luck with that gown, either.

"I like dresses," she says. "I think adult style dresses, you don't ever see them in children's sizes, one, but two, I've never actually seen them on my body so it's an uncomfortable feeling."

"The junior bridesmaid dress at the bridesmaid shop was supposed to fit my body, but it still didn't," she notes. "I still didn't have the boob area for it."

RELATED VIDEO: I ​Am Shauna Rae: 22-Year-Old Woman 'Stuck' in Body of an 8-Year-Old Says Mom Gets 'Negative Attention'

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Shauna then reveals in a confessional: "I started sewing my own stuff I think when I was 16 because I wanted to actually have clothes of my own."

"But finding clothing in the adult section and actually making it work to my size when it's already made, taking it apart ruins the fabric and you should've just started from scratch," she continues. "I think it depends on what's in the store and then I decide by looking at it if I like it whether I can alter it or not, and if I can't, I leave it."

I Am Shauna Rae airs Tuesdays at 10 p.m. ET on TLC.