"What happened three years ago, frankly, was a mistake," Drever, 26, told The Canadian Press in an interview Thursday.
"I wasn't aware of the premise of the photo beforehand and I was just asked to do this, and I did it.
"As soon as that picture was taken, I regretted it."
The photo is the latest in several questionable shots to surface since Drever won the Calgary Bow seat in the May 5 election. The pictures have sparked petitions demanding that she quit or be removed.
One Facebook photo is of Drever at age 19 and in dark glasses as she hams it up beside a marijuana T-shirt. Another shows a disembodied hand, not Drever's, giving the middle finger to the Canadian flag.
Drever, a third-year sociology student at Mount Royal University, said she just wants to get on with her new job.
"I am very disappointed in myself that I let (people) down. I really want to prove that I can do a good job."
Incoming premier Rachel Notley has accepted Drever's apology and has asked her to develop a plan to heighten awareness of violence against women.
Drever said she will do that and pointed out that she has been working for a long time with women's groups in Calgary, pushing for women's rights and combating violence.
"I'm passionate about women's issues because of my lived experiences."
Drever said her earliest memories of childhood are of abuse involving her mother and her mother's partner.
"There was a lot of screaming, a lot of scary sounds. Banging and crying, things like that."
She and her three sisters would retreat to a bedroom and close the door to "try and hide."
She was removed from the home when she was five and placed in foster care. From then, until age 16, it was a transient life: in one foster home, back with relatives, back to foster care, back to her grandmother.
"I've had first-hand experience witnessing violence against women," said Drever.
"And now that I'm a (legislature member) ... I am just so excited that I can help families like that because I can actually relate to them."
Her interest in politics peaked after high school, she recalled, inspired by listening to NDP MP Niki Ashton and reading "Black Like Me," John Howard Griffin's painfully personal work on race relations.
She was active in Calgary's music scene and agreed to pose for a cassette cover photo for the band Gatekrashor. When she got to the photo shoot, she said she succumbed to peer pressure. She posed on her back, legs apart on the concrete against a chain-link fence, and restrained by one of four men while another stands over her with a bottle.
The title of the album: "Fear of Attack."
"After doing it, I recognized it right away: the problematic imagery of that photo. I think it sends the wrong message to young women."
Now she is preparing for a new life shuttling between the legislature in Edmonton and her home in Calgary, where she lives with her grandmother and helps raise a four-year-old niece.
"I want to help out and help raise that child and be a real good role model for that child because she is very special to me."