Mike Fisher and singer Carrie Underwood arrive at the 52nd Annual GRAMMY Awards. Credit: Jason Merritt/Getty Images

Carrie Underwood and Mike Fisher agree about most everything, with one major exception: the number of children they hope to have.

In a joint interview on Oprah's Next Chapter, Underwood, 29, says that while Fisher, 31, grew up with "three siblings, I think two is a good number to have," the country crooner tells host Oprah Winfrey, 58. "We'll see. We'll cross that bridge. I don't want too many."

Fisher insists he'd be happy with "two or three" kids, but Underwood joked that usually, "He's like, 'I want seven!'"

Though Underwood and Fisher don't have immediate plans to start a family, Underwood predicts her husband of nearly two years "is going to be the best dad ever, and that makes the whole parent situation seem much better."

The "Blown Away" singer also admits that she still "can't believe" she's off the market. "Sometimes I still have those moments where I can't believe I'm married. I spent 27 years not being married and I kind of got used to it," Underwood says. "But now, the more I do it, the more I'm able to think more of 'we.'"

"For the first year of our marriage, I still would give people gifts and write: 'Love, Carrie,'" she says. "And I'm like, OK, now I'm 'Carrie and Mike' -- there's two of us now. But I'm getting better all the time."

Oprah's Next Chapter airs Sunday at 9 p.m. EST on OWN: Oprah Winfrey Network.