My son, Lucas, grinned as he traipsed through the door and dumped his schoolbag in the hallway.
I immediately spotted his prefect badge shining on his blazer.
"I'm so proud of you," I said, beaming.
I wasn't surprised that Lucas, 17, had been voted a prefect.
He'd always been smart and sociable – ever the doting older brother to his sister, Alisha, 14.
He was determined to study chemical engineering at uni so he buckled down in his studies.
I was surprised when one afternoon he texted me during school.
My left knee is sore. Can you book a doctor's appointment?
I figured he'd gotten into a scuffle on the school oval but an x-ray revealed a sinister lump.
"It's either cancer or a bone infection," the doctor explained sympathetically.
"You'll need an MRI before we can know."
I put my arm around Lucas, but he was frozen in his seat.
I felt the same, but had to put on a brave face.
"We don't know anything for sure," I soothed. "You'll be fine."
I held Lucas as he stumbled back to the car in shock, tears pricking at his eyes.
That made me lose it, too.
My husband, Les, was away at work but when I called him he dropped everything to drive the few hours home.
Lucas went through PET scans, MRIs, biopsies and blood tests, still completely gobsmacked at what the doctor had said.
He'd always been perfectly healthy, so even when we were called in to see a specialist, I had faith he'd be okay.
But the surgeon looked grim.
"It's aggressive osteosarcoma," he confirmed.
He explained that Lucas needed chemo to shrink the tumour before they could operate but the words wouldn't sink in.
My fit, healthy boy had cancer. How could this be happening?
"You can breathe now," the surgeon reminded me.
I blinked. I hadn't even realised I'd been holding my breath.
"It'll be okay, Mum," Lucas choked bravely, putting his arms around me.
He was only 17 and yet he was comforting me.
It was so typical of him to care for others in the worst moment of his life.
At home, I tried to keep up our routine.
"Can you take out the bins?" I asked Lucas.
"I can't," he shrugged. "I've got cancer."
A cheeky grin spread across his face as he chuckled.
I giggled, too. Faced with our worst nightmare, laughing was all we could do.
One week later, Lucas started chemo.
Since his cancer was aggressive, the treatment was intense and my son was left bedridden in hospital for four days after each round.
Woozy and weak, he struggled to even get out of bed.
Still, he was determined to sit his final exams.
At home he sat in his room, furiously scribbling down notes.
The chemo made him so sick he had to keep a bucket beside him.
"You don't have to do this," I pleaded.
But he was determined.
Two months later I bit back tears as he was wheeled into surgery to remove what was left of the tumour.
"We got everything out," the surgeon told us afterwards.
A huge weight was lifted from my shoulders.
Lucas only needed another three months of chemo, to kill off anything left behind, before he was out of the woods.
When he started treatment again, he mustered the strength to sit one exam in hospital.
After that he was too sick to sit the others but, based on his previous marks, he was still accepted into his dream course at uni.
I'd always known my son was strong but even I was surprised.
And with his 18th birthday only two months away, we could finally see a light at the end of the tunnel.
But even though he was cancer free, chemo ravaged Lucas's body more than ever and he struggled to recover from each session.
After two months, his kidneys were struggling to flush out the chemo toxins and his organs suffered.
By the next round of chemo, he'd developed a heart problem and was suffering from chronic kidney failure. He needed daily dialysis.
"What the hell is going on?" I sobbed as Les held me.
We were heartbroken. It felt like after all this, we'd stumbled at the final hurdle.
Over the next few weeks, Lucas's body was so overwhelmed by the chemo toxins, he developed pneumonia and a lung infection.
His body was shutting down.
The one thing meant to save him was taking him from us faster than we could prepare for.
"Is he going to die?" I choked to the ICU nurse.
She held my hand.
"Not today," she said.
Sobs wracked my body as I realised my boy wasn't going to make it out alive.
I tried to put on a brave face.
Lucas saw straight through it.
"Tell me what's going on, Mum," he croaked.
The doctor waited until Les arrived to break the news.
"You only have a few weeks left," he admitted.
He just nodded, as though he'd been expecting it.
"You have to fight, harder than you've ever fought before," I begged.
His 18th birthday was days away.
He deserved the freedom of adulthood, the chance to make his own mark on the world.
What if he never got there?
I'd bought him a card so Les, Alisha and I could tell him how proud we were of him and that we loved him dearly, but I hadn't gathered the strength to write in it yet.
Instead, I spent every minute at his bedside, praying for a miracle.
When the clock struck 12am on his birthday, Alisha, who'd been sleeping in a spare room at the hospital, bounded in.
"Happy birthday, Lucas," she cheered. "You can go to nightclubs now!"
Behind his oxygen mask, he smiled.
How could I wish him a happy birthday, knowing he was about to die?
Within hours, Lucas was struggling to breathe.
He was hooked up to so many monitors we couldn't hug him properly.
Instead, we put our arms over his shoulders and held his hands.
"It's okay to let go. I love you," I whispered and just like that, he slipped away.
Losing him was instantly unbearable.
More than 600 people attended his funeral, proving how many lives he'd touched.
Months passed and I struggled to deal with my grief.
How could such a good person be taken away so young?
His 18th birthday card is still blank, sitting in my bedside table.
I can't bring myself to throw it out.
But I wanted him to be remembered.
To help process my feelings I wrote a biography, 18 Forever, about Lucas's life.
The day I had him was one of the happiest moments of my life so I never expected his birthday to fill me with such heartache.
My son will never grow older than 18, but I'll make sure he's remembered forever.