Gregg DeGuire / WireImage 1 / 6
Gregg DeGuire / WireImage 1 / 6

By Jessica Wedemeyer, reporting by Heather Newgen

Wedding bells are ringing for Whitney Port! The "Hills" alum is set to become the future Mrs. Tim Rosenman after her love of two years popped the question during an Australian vacation in November 2013. Though the newly engaged duo have yet to set a date, wedding planning is already well under way for the reality-TV star and her sister, Ashley, a professional wedding planner.

"I'm too detail orientated -- and I know what I want," Whitney told Wonderwall at QVC's 5th annual Red Carpet Style event in Los Angeles on Feb. 28. "[Ashley's] the more organized one, so we're working together to create everything. … I just met with her a couple days ago to talk about some stuff, but I'm pretty calm about it -- it's not an everyday type of thing."

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Ashley isn't the only one pitching in when it comes to planning Whitney's big day. According to the reality-TV star, her fiance, who served as an associate producer on "The City" back in 2008, is already a hands-on groom: "He's pretty involved," she says. "He wants to know everything that is going on, which helps me."

The fashionista, who plans to design her own wedding dress -- "But I haven't started working on it yet," she says -- also insists her big day will be a "medium sized" affair.

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"It's not going to be big," she says. "I don't need the whole huge deal. … I know that it's one day and one night. I'm not going to go crazy over it."

The laid-back bride isn't sweating little things like looking perfect on her wedding day either. Though she works out five days a week -- "It just feels good to me," she says -- Whitney hasn't kicked her workout regimen into overdrive in advance of her trip down the aisle.

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"Honestly, I'm not even really thinking about that," she says. "It's more of just a lifestyle that I'm trying to adopt. … I try to stay healthy. Working out is important for me physically, mentally and emotionally. I spin. I try to do some yoga, and I eat pretty healthy."

It certainly doesn't look like the "Hills" alum will need to improve upon much before her big day! The super-slim reality-TV star glowed while showing off her enormous rock at the pre-Oscars bash.