Rita Nganwa, 17, says the failure of her school to give her adequate careers advice made her waste a year of her life.
She thinks all students should be given one-to-one careers tutoring from the age of 15 to allow them to build up a relationship with the careers adviser.
Ms Nganwa, who took her GCSEs at St David's and St Katharine's School in Hornsey, north London, believes the school failed to give her the vital information needed to help her decide what to do after 16.
"There was one day where we could talk to the teachers about careers, but it was too much to take in one day. I needed more personal advice."
Ms Nganwa left school at 16. Unable to find Islington's local careers office, she ended up at one in Camden.
She decided to take English and History A-levels at City and Islington College but admits that "no one really helped me apart from my mum and dad".
Jennifer Hodge, 16, says her experience at Elizabeth Garrett Anderson school, north London, was pretty similar.
She was also dissatisfied with the careers advice. No one explained the range of courses available or where they could lead to.
The girls say that even now they are intimidated by careers rooms full of books and feel alarmed when faced with Universities Central Admissions Service forms.
Says 17-year-old Ashabi Aji-kawo: "The time at college goes so fast and before you know it you have to make more choices. If you want to get careers advice you have to motivate yourself, but what you really want is for someone to come and explain it all to you."