Lovato, 21, who ended up in rehab in 2010, admits that since she had grown-up responsibilities, she thought she could act like a grown-up, too.
"My parents tried to control me, but I'd be like, 'Oh really, I'm grounded? Well, I pay the bills,' " she says. "They did the best they could. And I think that's why a lot of young stars struggle when they're making money or providing for their family."
The X Factor judge, who battled addiction issues, an eating disorder and cutting, has previously said she "had a nervous breakdown," while on a world tour with the Jonas Brothers.
"My mentality was 'Work hard, play hard,'" she admits in the magazine's Dec/Jan issue. "It was hard to listen to the word 'no.' I wanted to make my own rules. I thought that if I was adult enough to get there, then I could party like an adult. And obviously, I couldn't."
"I would like to separate myself from being the girl who overcame her issues, or the Disney chick who ended up in rehab while she was still on Disney," she says. "I don't want people to hear my songs on the radio and be like, 'Oh, that's the girl who cut.'"
But her honesty has helped others and she acknowledges that. "Now I have probably the best relationship between any artist and their fans, because I have no secrets."