is one of Hollywood's finest stars, so it's surprising to hear she suffered from insecurities when she was younger.

Starring in the new  film 

, the Aussie actress has reminisced about her days attending North Sydney Girls' High School. In a new interview with , Kidman said she always felt self-conscious about her height during her teenage years.  

"I was a teenager who wouldn't conform, but I had a lot of fears and insecurities because I was very tall. I was 5ft10in' [1.77cm] by the time I was 13 years old," she told the magazine. 

But she decided to make the most of it, and chose a formal dress that would not hide but celebrate her features and personality.

"I wore a 1920s flapper dress, which goes along with my 'not conforming' sensibility," she recalled. "I bought it in a vintage store and I just loved the idea of a flapper dress, it was black and white beading — it was definitely not tulle and big skirts. I think I remember getting a little drunk too, which is probably a lot of people's experiences at their prom or formal."

Kidman has since swapped Sydney op shops for designer labels, but she'll always remember where she came from.

The actress revealed she and her family didn't have much when they first moved to the US when she was a child — her mum Janelle was a nursing instructor and her dad Antony was a psychologist, who often worked for free. 

"I've always been aware of privilege, because both my parents came from nothing," Kidman said. "When we moved to America, we had nothing. My parents had to go to the Salvation Army and get a donated mattress, which we all slept on, while my mum helped put my dad through his PhD as he came from a very poor family.

"When he became a psychologist, he would offer his behavioural therapy for nothing if they didn't have any money, because he just wanted to help. I grew up with one of the gentlest, kindest fathers who was a giver and my mother was a nurse, so my family had that social conscience."