Ashlee Simpson "happy to be" getting married

Ashlee Simpson didn't mention her widely reported pregnancy during an interview on Ryan Seacrest's KIIS-FM radio show Thursday morning -- but did open up about fiance Pete Wentz.

"I didn't know I'd be getting married right now, but I'm so happy to be!" Ashlee, who was calling from her mother's hotel room at the Ritz-Carlton in NYC, said. "I'm a lucky girl."

But she kept mum about how Wentz proposed, saying, "That part I am keeping sacred, but I will tell you that it was very thoughtful, and he did a great job.

"Of course, it was thoughtful," she added, "He's like that."

Simpson -- who flashed her new engagement ring in NYC Wednesday — said she loved her rock.

"It's definitely a big diamond!" she gushed. "I go, 'Oh, my God, I can't believe it's on my hand!'"

When asked if she'd be marrying the Fall Out Boy rocker anytime soon, Simpson, 23, replied, "I can't tell my secrets," but added, "my mom loves Pete, so does my dad!"

Seacrest avoided asking flat-out if she were pregnant, but he did ask the singer whether she'd be drinking booze during her promotional tour of NYC this week, to which Simpson replied, "Who knows? Maybe."