"I have mixed feelings," she told PEOPLE on Friday at Tao Las Vegas, where she was celebrating her big birthday a few days early. "Sometimes I'm like, 'Oh my god, I'm turning 30,' and I'm freaking out."
"Like, it sounds so old," she said. "And then the other half of me is like, I feel so accomplished and it's really no different than 29."
But her family isn't letting her forget about the milestone.
Brother Rob Kardashian said he is already giving his sister grief about her age, although she doesn't actually turn the big 3-0 until Oct. 21.
"We've literally been clowning her all day," he told PEOPLE at the bash sponsored by the video game Fallout: New Vegas.
Mom Kris Jenner, meanwhile, has let her daughter know that she had four children by the age of 30.
"I've definitely heard that a few times," Kardashian said.
Later, during a toast to her daughter during dinner, Jenner offered her sincere thoughts – plus a little plea. "I wish you all the love and happiness," she said. "No pressure – but if you happen to find a husband and have 1,000 kids, I'd really be happy."
After the speeches and dinner, guests continued partying inside Tao.
And Kardashian, who will continue her birthday celebration Saturday in the Big Apple at the 10 year anniversary of Tao New York, couldn't seem happier, sipping champagne and White Russian cocktails and laughing with her family and friends, like Kelly Rowland, from a private skybox overlooking the club.
She was later presented with a three-tiered red and black birthday cake before moving the party onto the dance floor where she and Khloe Kardashian took turns hyping up the crowd on the microphone.
Partying aside, the socialite said that although she is "freaking out" about aging another year, she isn't changing anything about her romantic life: She's not rushing to find a boyfriend.
"You know, I've always been one to say you don't need anyone to define you," she said, donning a metallic dress by John Richmond. "I've very happy with myself. I'm married to my career. I'm married to my family."
"I have the best friends that any girl could ask for," she said. "I'm so happy and fulfilled."
Reporting by JENNIFER GARCIA