Media playback is unsupported on your device Media caption Megan's family had to pay privately for surgery

"I was really sore. It was really painful. And I felt really drowsy and sick, and just wanted to go back to bed," says Megan, watching a video of her first steps after major spinal surgery.

Wearing pyjamas and fluffy slippers, she treads carefully, held up on either side by a Turkish nurse.

Megan flew to Istanbul for private surgery late last year, having been told she faced long delays for an operation to fix the deformation of her spine, which was causing her problems breathing.

When the healthcare trust in Belfast told her parents it would be at least a year before she could have the procedure, they felt they had no choice but to fundraise for treatment.

Through the generosity of strangers, the money was raised - but surgery to insert four metal rods into her spine was painful and expensive, costing about £30,000.

Just a few days after treatment, 14-year-old Megan had to board a plane home to Northern Ireland.

"But I was so happy, because I just wanted it over and done with, and to get back on the road to recovery," she says.

Image caption Rods were inserted into Megan's spine

For her mother, Karen Fleming, though, the upset and uncertainty still plays on her mind. And she is angry on behalf of dozens of other children still waiting for similar treatment.

"It's a shambles. It's a mess," she says.

"It's no fault of the surgeons. It's no fault of the nurses. But it's awful. It's just seeing your child in pain every day, knowing that you can't help them. And the only way for a lot of families is to fundraise, or actually to remortgage your house."

In Northern Ireland, targets say most patients should be seen within nine weeks and none should wait over 15 weeks.

Curvature of the spine

Just a few miles away from Megan's home in Carrickfergus, we visit 16-year-old Sophie Tanner in Belfast.

She waited 20 months for the same operation, to correct curvature of the spine, before it was cancelled the day before surgery.

Her parents were delighted when Sophie was then offered the procedure in Stanmore hospital, in Middlesex.

It went well but took 14 hours instead of the eight it was supposed to.

Nevertheless, the operation has taken the pressure off her heart and lungs and she has made a very good recovery.

But Sophie's parents say having to wait as long as she did was unacceptable.

"What most people in Northern Ireland want is the same treatment as the rest of the UK," says her father, Eddie.

"We're part of the UK, so we think that the waiting lists should be similar. We pay taxes. We pay National Insurance. We would expect the powers to be to make sure that places are pretty equal."

Surgeon: 'We have no choice'

Spinal surgeon Niall Eames, in Belfast, says the health service is doing what it can to restructure itself and offer surgery faster. But in the short term he has no choice but to tell many children they need to expect long waits.

"Telling a child that they can't have the operation when they need and want the operation - it's completely inappropriate," he says.

"Obviously it's terrible for the patients. It's awful for them. But equally for the healthcare people involved in the caring, the managers, the nurses, the consultants, the staff - it's awful not being able to offer the treatment we know they require in a timely manner."

New data from the Royal College of Surgeons shows the problem in Northern Ireland is getting worse.

At the end of 2017, there were more than 14,000 patients waiting over a year for treatment, with more than 3,000 waiting over two years.

In Northern Ireland that represents nearly one in 100 people.

By comparison there are about 1,800 people waiting over a year for surgery in England.

The Northern Ireland Health and Social Care Board, which runs the NHS, said: "The system is under huge pressure and the waiting times experienced by many patients continue to be unacceptable.

"There simply isn't either the money or required staffing levels to sustain the current model of care."

But the Department of Health in Northern Ireland said it had announced a £30 million investment in tackling hospital waiting lists in the current year. However, the money has not yet reached the frontline.