The Saturdays singer told the News of the World that she was not content with just her UK accomplishments.
"This is what I've wanted since I was a kid," she said. "It's a tough business. When I couldn't make it before, I tried to train as a nurse and I was so miserable that I just had to go back to singing.
"I want this so much. I want to break Europe and America."
She added: "If we weren't serious about the band, we wouldn't have gone through the real pain of getting rid of our manager, but it was something we had to do to get things right."
The 28-year-old also spoke about her "serious" relationship with England rugby player Ben Foden.
"I'm an expert in bad relationships which is why I know when I've got it right," she told the paper.
"I want a great career, but I want a great relationship, too," she added. There's no point in being rich and successful but also on your own with no one to share it all with."
The Saturdays release their new single 'Missing You' next week.