Carol Donald says she feels Darcy McGuire, 8, may have had a chance at surviving bone cancer chordoma if it has been picked up sooner.
She said she first took her little girl to the doctor when she was three after finding a lump in her spine.
But Carol claims medics assured her there was nothing wrong.
Even when Darcy began losing weight and was in pain, the Scottish mother, from Glenrothes, said doctors told her it was "growing pains”.
After discovering the cancer had spread to her ribs, lungs, arms and legs, the eight-year-old has started to plan her own funeral.
“This is definitely not something any mother should have to do with their eight-year-old daughter," Carol said.
The mum-of-five, continued: “I was so angry and frustrated because I always knew, as her mum, that something was being missed.
“I’ve always been extremely honest with Darcy about her illness and she knows that one day she is going to die.
“Darcy has helped plan every single part of her funeral along with me.
“When your child is given a terminal diagnosis, they don’t have a choice or say in their death – but I was determined to give Darcy something she could control.
“This is definitely not something any mother should have to do with their eight-year-old daughter.
“If this had been found earlier, I have no doubt Darcy could have stood a chance at beating this cruel disease.”
“We continued going back and forth to GPs and specialists, who made us feel like we were wasting their time.”
Brave Dacey is raising money for the charity Children’s Hospices Across Scotland (CHAS), which has provided valuable help and support to the family.
Both NHS Lothian and NHS Fife said they were unable to comment.