The `Not Fair` hitmaker - who is due to give birth to her first child with boyfriend Sam Cooper in February 2011 - admits she was terrified of something going wrong after previously suffering a miscarriage two years ago, when she was dating Chemical Brothers star Ed Simons.
She said: "I came off the pill, and weirdly, a week later it happened. But then it was really difficult - I had complications.
"I had about a week and a half of really heavy bleeding and had to have lots of scans, that`s when I had to cancel my gig in Spain. I`ve been living in fear for the past three months."
The 25-year-old star also admitted she regularly skipped meals, replacing food with alcohol, until she fell in love with 32-year-old Sam last year and transformed her life.
Asked if she had suffered an eating disorder as a teenager, she told the Sunday Telegraph magazine: "Not then, but last year I wasn`t eating. I would drink a pint of Guinness as a meal.
"It was only when I got together with Sam in June that that stopped - and that`s also when I stopped using twitter because he said, `This is weird, why are there millions of people in the room with us?` So I cut myself off from everything - and I was so much happier."