'I want you here.' Grieving mum shares photo of daughter's car seat with crushing message.

Sarah Walton should have been strapping her four-year-old daughter into her car seat to keep her safe on their way back home.

Instead, she was buckling up an urn containing her daughter’s ashes.

Sarah shared an image on Facebook of the heartbreaking moment, writing that Ellie “should be here”.

“Driving you home the other day, I was scared, but buckling you in felt normal,” she wrote.

"Even though none of this is normal, none of this is right. You should be here. Death is so selfish baby girl. My heart is broken."

Ellie was diagnosed with a brain tumour at just four months old. An ultrasound, CT scan, and MRI revealed the tumour was one third of the size of Ellie's newborn brain.

Five months after she was born, Ellie underwent a nine hour surgery to remove the tumour. At just eight months old, Ellie began chemotherapy.

When Ellie passed away on January 15 this year, she had undergone 17 surgeries, 28 rounds of chemotherapy and 42 days of radiation.

Two months after her daughter's death, Sarah said her daughter is "in a better place".

"Yet no place is better than in my arms. I know you're happy and pain free, and yet I want you here," she wrote.

"It's been two months since I last kissed your cheek or played with your hair. It's been two months of pure torture, agony, and despair. All I want back is our daily life, whatever they entailed, I want it back.

"I want hospital visits back, and chemo back, I want your laughter, and your joyous heart back. The things that brought my heart so much pain, only a few months ago, I so desperately want back today."

Sarah decided to share the photo of her daughter's ashes - housed in a temporary urn which Sarah decorated with pink and blue lace, a photo, her name and her favourite pair of glasses - to raise awareness of her daughter's fight.

LISTEN: The Well discusses the seven stages of grief.

"I would have never known to live every moment as your last, and I would have never known what true bravery, strength, and courage looked like," she wrote.

"This will change baby girl, I will make it change. I never want another mum to feel this way, and I will fight for these other kids so that no other mom has to buckle in ashes of their babies."