Beyonce and Jay-Z attend the New York Knicks vs Miami Heat basketball game on April 15, 2012 in New York City. Credit: James Devaney/FilmMagic

Blue Ivy Carter may not be a "Single Lady" forever.

At the Met Gala in New York City Monday, new mom Beyonce Knowles, 30, said she and husband Jay-Z, 42, have talked about expanding their brood. "I definitely want to have more," Knowles told Entertainment Tonight. "I don't know how many. God knows. I don't know yet."

Just don't expect a pregnancy announcement in the near future. "I don't know about soon!" Knowles giggled.

The singer -- who is currently rehearsing for a special three-night engagement over Memorial Day Weekend at Revel Beach's Ovation Hall in Atlantic City, New Jersey -- added that she has "such a full life. I feel like now I know the reason that I was born."

Knowles said she's "been working really hard" to get her post-baby back. "There are no secrets. [It takes] discipline!"

She's not kidding. The 16-time Grammy Award winner works out five days a week with trainer Marco Borges. "We do cardio and plyometric moves like lunges and jumps on and off a bench," the pro recently told Us Weekly.

Knowles, who is 5-foot-9, avoids processed fare and sticks to whole foods like vegetables and grilled meats. "You don't have to eat only celery sticks," Borges advised. "Be sensible and exercise constantly."