"They just put it down to back pain from the baby leaning on my spine," she said.
"I demanded they do a blood test and they found my kidneys were failing from the painkillers they had given me, and when they put in the stents in the kidneys they found the cancer."
She has not formally complained and is instead pinning her hopes on a fundraising campaign to pay for alternative treatments that she hopes will extend her time.
Cousin Louise Henare has started a Givealittle page to raise money for the other treatments, including ozone therapy, vitamin C injections and traditional Maori kawkawa medicine.
Mrs Ryder's partner of 17 years, Klintyn Ryder, whom she married in May after the cancer was diagnosed, has stopped working as a concreter so that he can look after Kourtney and the children.
"I can't really do anything," she said.
Finances are tight because the family now live on a benefit. They had to give up their rental home in Beach Haven and live with Mr Ryder's parents in Glen Eden.
Cancer Society medical director Dr Chris Jackson said cervical cancer had become a rare condition, especially in young women, since three-yearly smear tests were started and the Human Papilloma Virus vaccine was offered to teenage girls from 2008.
"So this is an enormous tragedy and enormously distressing for a young mother," he said.
He said vitamin C injections were an experimental treatment and he did not have any knowledge or experience of any potential benefits from ozone therapy.
Otago University Professor Margreet Vissers said she was about to start recruiting patients with bowel cancer for a clinical trial of vitamin C injections in Christchurch.
"There are definitely people for whom this works, and there are definitely people who are living quite a lot longer than their doctors ever expected even if the tumour hasn't gone, but we can't predict who they are," she said.
Her research is being partially funded by the Health Research Council but she has also set up a Vitamin C for Cancer Trust to raise the rest of the $1 million cost of the trial.
Donate to help Kourtney and her family here: givealittle.co.nz/cause/help4kourtney