The singer-and-actress - who got engaged to hockey player Mike Comrie last month - has already started planning her nuptials and is in complete control of all the preparations.
Hilary - who has been dating Mike for two years - said: "We want to keep it small. Mike's like, 'Whatever you want!'"
The star says she is planning a "traditional" ceremony and is looking forward to choosing her dress, though she fears looking like "a big cupcake".
She explained: "I want it to be traditional. I don't want it to be too big and overwhelming, because I'm so small. A big dress would make me look like a big cupcake!"
Mike proposed to Hilary during a romantic break in Hawaii with a $1 million 12 carat diamond ring and although the 23-year-old star was delighted by the surprise, she was disappointed when paparazzi photographs of their trip
appeared on the internet.
Hilary - who was snapped photographing her engagement ring on her mobile phone - told website Hollywood Life: "It was awful. We had no idea they were there; it was weird.
"I hated that. I was taking a picture of my ring and sending it to my mom!"
Hilary's sister Haylie Duff recently revealed the 29-year-old sportsman's proposal came as a complete shock to her sibling.
She said: "She was completely surprised. I don't think that happens all the time. I think most of the time people figure it out or have some idea that it's going to happen, and I think it's great he was able to do a surprise like that for her."
Although exact details of the proposal remain secret, the 29-year-old sportsman's gesture was "very romantic".
Haylie added: "I adore him. He's wonderful... very romantic."