"Oh gosh, my friends and I had such fun!" she gushed.
"We loved Britney Spears, Christina Aguilera and the Backstreet Boys... I remember dancing to their songs at school dances."
The reason for the nostalgia is that part of her latest film - Love, Rosie - sees Collins' titular character at school.
"When we shot those high school scenes, it was like being transported back in time. The female characters were all inspired by fashion icons of that decade... Suki (Waterhouse) dressed like Britney and Christina, and I was styled like Natalie Portman."
The rom-com follows Rosie's complicated platonic friendship with best pal Alex (Sam Claflin), and how her unplanned pregnancy puts a halt to her best-laid plans.
But Collins' school days were different from most. The 25-year-old has been on the entertainment circuit since she was two.
Staring as a child actress, Collins spent her teen years as a TV host, magazine columnist, model and even earned the International Model Of The Year nod from Spain's Glamour magazine.
But even teen models occasionally get smacks of the baton from the fashion police.
"I went through a phase where I had blue hair, and wore frosted blue lipstick...it was super bizarre!" she confessed.
Looking at what she wore for the interview, Collins is still into blue, only more tastefully than in the past.
She looked captivating in a stunning navy bustier dress with full ballerina skirt.
"Don't ask me where it's from, I can never remember," she laughed.
Interviewing Collins proved to be a balancing act. She readily chatted about clothes and boys like a close girlfriend, but drew the line at revealing too many personal facts.
The daughter of musician Phil Collins and his second wife Jill Tavelman is well-versed in keeping the press at a comfortable distance.
She was happy to talk about what Rosie had gleaned from her relationships.
"When 18-year-old Rosie decides to keep her baby, she moves forward in a positive way.
"She really matures and realises she needs a relationship with a best friend she can trust."
But then she declined to share what she learnt from her own relationships, such as with Abduction co-star Taylor Lautner or Jamie Campbell Bower from The Mortal Instruments: City Of Bones.
Collins played the teen heroine in the Young Adult adaptation last year. It flopped.
But Collins was unfazed, assuring us that she "had the best time making it".
FAIRLY THICK SKIN
She has a fairly thick skin, which was evident when the subject of her thick eyebrows arose.
"Some people have pretty negative things to say about them. They're natural, and anything that's natural in Hollywood is something to be pinpointed and talked about. "But they're part of me... I'm not shaving them off or anything!"
She added with a confident grin: "I could embrace my eyebrows or let them bother me every day. I choose to embrace them."
While Love, Rosie is something of a throwback to Brit rom-coms - such as her favourites Love, Actually and Notting Hill - Collins dismissed the idea that such films are of lower status.
"They get this reputation of being cheesy. But the British sense of humour is more realistic. The awkward moments in Love, Rosie are actually the most funny and endearing.
"It's not just a love story or a comedy... I feel like there's a lot of heart and soul in there."
This article was first published on Oct 29, 2014.
Get The New Paper for more stories.