"Not that I have a husband to have one with yet, but someday I'd like a family – not a big one, but not a small one either," the singer, who is dating Ottawa Senator hockey player Mike Fisher, tells Self magazine in its January issue. "Two kids is good; three is fine. Four? Somebody's getting something done, because we ain't having five!"
While she's looking ahead to the future, Underwood also has put one giant item on her bucket list: "Before I die, I want to get rid of all my money," she says.
"Recently, I started a foundation to benefit my hometown [the Checotah Animal, Town and School Foundation: C.A.T.S.]," she says. "I'm looking forward to doing a lot of good for a community that's a big part of why I am who I am."
Underwood, 26, also opened up to the magazine about her biggest pet peeve: messiness. "It drives me crazy when people put stuff in the wrong place," she says. "When I have people over and they try to help clean up, I'm like, 'No, I've got it!'"
When she's not cleaning up at home, Underwood is keeping in shape – with lots of help from Jillian Michaels. "I have Exercise TV on cable," she says. "Jillian Michaels's videos will kick your butt. She's my trainer, and she doesn't even know it!"
But the trainer isn't the only thing keeping Underwood healthy. The singer lowered her sugar intake, including cutting out soda. Now, she says, "I have a lot fewer breakouts."
"People have asked me, 'What are you doing differently?' I'm honestly just eating healthier," she says.