Jefferies told Insider she didn't wear the skirt in the vehicle that transported her to the wedding, as she didn't want it to wrinkle.
Her friend gave the gown to a venue attendant when they arrived, who took it to a storage room with the rest of their belongings by mistake.
"The rest of the girls in the car with me were rushed inside to take their seats, so I was left alone in the final moments before walking down the aisle," Jefferies said. "As soon as I got out of the car behind them and entered the venue, I already heard the song playing that I was walking down the aisle to, so I didn't even have time to think."
She didn't realize she didn't have the skirt until the ceremony had already begun.
"The officiant was saying his first few lines when it dawned on me and I absolutely panicked. I kept thinking, 'This cannot be real. This is not happening,'" she said.
As Jefferies shared with Insider, she had a nightmare about forgetting the skirt just days before the wedding, which made the experience even stranger.
"One of my recurring nightmares was forgetting something important on the wedding day, whether it was putting makeup on, my veil, or the overskirt," she said. "I was so excited to finally get the overskirt right, but I also had this fear of something not working out with it."