She was alive but the trauma had left her unable to walk or talk. She couldn't eat. She had to relearn how to live.
"It was crazy. We had to relearn how to do everything," she said.
"We had to get my tastebuds going again. So it started by licking a Jatz biscuit.
"Then it was eating half a Smartie - to this day I can't eat Smarties because my brain thinks I'm full after half a Smartie."
She vividly remembers the struggle to teach herself to walk again.
"Learning to walk was really hard and tiring and painful, but there was a little girl in hospital with me, and she used to knock on my window and blow me kisses, and I used to get frustrated that I couldn't go and see her," she said.
"That gave me the strength to keep going, so I could go and see her."
What she will also never forget are the friends she lost during her on-and-off two-year hospital stay.
"I lost nine friends to cancer in that time," she said.
"It's so tough to see your friends die, and I have PTSD (post-traumatic stress disorder)
and survivor's guilt because of that.
"On the outside I am back to normal but my insides are all messed up still."
It's one of the reasons she will soon jump out of a plane, to support the Australian Children's Cancer Institute's Dare The Boss fundraising initiative.
Nikki will be skydiving for the cause with the Austral Bricks Brickworks team, helping meet this year's Dare The Boss fundraising target of $400,000.
"I'm really excited," she laughed. "I can't wait."
COME STRAIGHT IN
Nikki was a Year 8 pupil at Westfield Sports High, in Sydney's west, when she started to become sick - ill with nothing in particular, just always tired and never well. Away at an annual softball tournament, she started to get worse and decided to get some blood tests done on her return to Sydney.
"I had grown up playing sport and having a normal childhood," she told news.com.au
"But I was always sick - it was hard to pinpoint but I was always lethargic and never quite well.
"When we got back to Sydney my mum was driving me to school and I started gagging and I couldn't breathe properly.
"So I went to the doctor and had some tests - and he called at 6am the next morning and said to come straight in."
"When we got there, the receptionist had tears in her eyes ... she took me to a separate room and my doctor came in with tears in his eyes, as he has known our family for so long.
"He said I had leukaemia and that I was to go to The Children's Hospital at Westmead.
"He walked out of the room and I was too afraid to ask if I was going to die, so I asked my mum.
"She looked at me and she said 'no - but it will be the hardest game of softball of your life'."
Nikki had bone marrow lumbar punctures to see what kind of leukaemia she had, as well as daily chemo for a week, when she started becoming weaker and sicker than normal.
"They put me in the bed to relax and my mum says she heard the TV remote drop, and I was having a seizure," she said.
Then Nikki went into a coma.
THERE'S SO MUCH TO LIVE FOR
Nikki has just completed a four-year nursing course at university. She plays touch footy. She loves to surf. She went to her school formal, wig and all.
"I get pneumonia and chest infections and the nerve damage is still there, and my short term memory isn't the greatest," she said.
"I also have dead bone through my body which is a chronic pain issue."
But she said the memory of her time in hospital continues to push her.
"When you see those people [in hospital] every day they become your family, and because I was one of the oldest in there, I felt like I had to be strong for the other kids because they looked up to me.
"I wanted to show them it could be OK ... and I always felt like it was going to be OK.
"I was never afraid because of what my mum said to me the day I was diagnosed - she helped save my life that day because I was never afraid.
Nikki said that although she'll never be the same after her diagnosis, she wants to use her experience to inspire other young people battling cancer.
"I feel like I've been given this chance to help other people."
"I just really want other people to know they are not alone.
"There are days it's tough and you want to give up, but there's so much to live for and there's always someone out there who gets it."
