"I am very detail-oriented, so I am kind of like a nightmare," she said of organizing her nuptials with planner Mindy Weiss on Good Morning America on Wednesday.
"I think in America, we call that 'Bridezilla,' " Lara Spencer joked.
"I think I'm beyond that," the Modern Family star said, laughing. "I have very good memory. If you show me swatches of things, I can in two months exactly remember, 'But what happened with the one with the little border that had the little print?' I'm really bad."
Vergara, 43, and her fiancé Joe Manganiello, 38, are set to say "I do" in November. The Magic Mike XXL actor proposed last winter while the couple vacationed in Hawaii.
How involved is the groom-to-be in the wedding plans?
"He's a pleasure to be doing this with," Vergara said. "He lets me do whatever I want."