Jessica Simpson keeps trying to get to the altar, she told Jay Leno on Tuesday's Tonight Show.
"We've had two different wedding dates, but he keeps knocking me up," she confessed of fiance Eric Johnson. "We're doing it very backwards!"
She added that with whatever next date they set, "I'll just keep my legs crossed."
Asked if the pregnancy was part of her "plan," Simpson said, "Oh no. Apparently it was a part of God's plan for my life."
She laughed. "I was extremely shocked. I was shocked because I was going through a lot of hormonal changes, trying to get back to the old, vibrant Jessica. And, you know, it was kind of like a one-night stand. And it happened, all over again!"
She said Weight Watchers was "as shocked as I was."
This pregnancy is different, she says, adding that she's due in summer. "I've been puking. I've been really, really sick," she said, but she is "trying" to be healthier.
"I was really happy to be pregnant and I just didn't ever step on the scale," she recalled about being pregnant with Maxwell, now 8 months. "I didn't realize you could gain that much weight that quickly."
Leno asked how much she gained and she wouldn't say, but it was probably "a lot more than doctors would recommend, but I had fun." Until she realized she had to really work hard to lose "over 50 pounds in four months."
Her favorite food? "Everything, Jay." She explained, "I didn't really make any healthy, good decisions."
She also talked about joining NBC's "dysfunctional family," as Leno called it. She's going to do a sitcom "loosely based on my life."
"About a girl that keeps getting pregnant?" asked Jay.
She said, "I will be playing myself, which is pretty easy."
(Copyright © 2013 USA TODAY)