Doctors are yet to give a final diagnosis on Axel's health issues, which are many and varied. Not only is he 14cm shorter and 4.2kg lighter than his identical twin, but his problems include physical development issues, deafness and recurring jaundice.
"We are currently bouncing between diagnoses. There's just problem after problem," Ms Crossley-Coe told the Northern Advocate.
Since December last year, she has visited the GP with her son 57 times.
"I am getting accustomed to it," she said.
Problems with Axel started before he was born - when Ms Crossley-Coe was 16.
In 2010, she was a high-achieving Year 11 student at Kerikeri High School, who was forced to leave due to health concerns, including swine flu and hyperthyroidism. It was during a heart scan a month later, she discovered she was 21 weeks' pregnant - with twins.
"It was pretty terrifying and I refused to believe it for two weeks."
But something was wrong - Axel was half the size of his twin and, at 27 weeks, Ms Crossley-Coe was diagnosed with twin-to-twin transfusion syndrome (TTTS), which means her placenta was being shared unequally by the twins.
"Axel was given less than a 5 per cent chance of survival, and Kyan's would be greater, if I chose to abort Axel. I decided against it."
Four weeks later, Ms Crossley-Coe gave birth to the twins by emergency Caesarean section. Kyan weighed 1.4kg (3lb 2oz) and was 41cm long, while Axel was a mere 510g (1lb 2oz) and 30cm long. "I wasn't allowed to see him [Axel]. I just saw a tiny body wrapped in Gladwrap."
Since then Axel has been leagues behind his brother, Kyan, in terms of growth and development.
"He was slowly gaining weight, but never getting on to the graph, while Kyan was soaring on the 50th percentile."
In August, after dropping a significant amount of weight, Axel was fitted with a feeding tube through his nose.
Then on Thursday doctors also discovered Axel was deaf. "I didn't expect that at all - it was a curve ball," she said.
Ms Crossley-Coe is now fundraising through the Givealittle website for HGH treatment for Axel, as he just misses the criteria for Pharmac subsidy - by 3mm to 5mm.
"Growth hormone in New Zealand costs around $10,000 a year. But the benefits are incredible. He will develop an appetite, and grow to the size of a normal adult. His bones will strengthen and his organs will develop," she said.
She is also fundraising to be able to buy a car to drive Axel to his appointments from Auckland to Kawakawa. "We need help. I'm a solo mum on a benefit."
To donate, visit https://www.givealittle.co.nz/cause/HelpAxelCrossleyCoe
