At 8 weeks old, Tilly who was diagnosed was given just two years to live after being diagnosed with a very rare genetic condition.
Her parents, Emily, 26, and Rob, 39, from Hertfordshire, received the devastating news just weeks after taking their newborn home that she had spinal muscular atrophy (SMA) - a serious genetic condition that means her muscles are extremely weak and don't function properly.
Tilly cannot walk, sit without support or swallow and the disease also affects her respiratory muscles, resulting in the use of a ventilator to help her breathing at night, HertsLive reports.
Every 15 or 20 minutes or so, either Emily or Rob has to use a suction machine, similar to what you may see at a dentist, to remove any excess saliva from her mouth since she's unable to swallow.
When Tilly was diagnosed with type 1 SMA, the most severe of the four main types, in 2016 the prognosis was bleak.
Her parents had to grapple with the news that Tilly would unlikely live beyond the age of two - but thanks to the power of modern science that all changed.
Mum Emily said: "At the time of [Tilly's] diagnosis, this particular genetic condition was one of the biggest fatal genetic conditions for babies.
"Instead of your muscles growing and getting stronger, they get weaker and weaker, so it affects everything.
"It affects your ability to move, to hold your head, to sit, and it also affects your respiratory muscles.
"Tilly needs support with her breathing at night and it also affects her swallowing muscles, so she's fed by a gastrostomy."
The charity SMA UK has been at the forefront of research into the condition and a trial for the drug Nusinersen, marketed as Spinraza, was going to become available.
However, at around six months, Tilly became gravely ill and was fighting for her life in intensive care.
"Although they said maybe two years [as a prognosis], it was more sort of seven to 12 months. Then she got really sick around six-and-a-half months and it was almost what they'd said and what I'd read from other people's stories."
She continued: "She pulled through and it's hard to think of that period because now I feel so hopeful with how she is doing, and I'm really proud of how she's doing.
"The face of the disease has changed."
At 10 months old, she was given a lifeline. As part of an expanded access programme, Tilly was given the treatment which she takes every four months.
"It's been incredible," added Emily, "and it's basically halted the progression of the disease.
"She's actually made a lot of gains. She can now sit up and has a lot of support, she has a spinal brace on.
"She can hold her head and she's been doing really well."
The treatment is a lumbar puncture into the spine, and Emily says it's been a "game changer" for families and individuals living with the disease.
"All these children with SMA who wouldn't have been expected to survive beyond two are now really thriving," she added.
As Tilly gets older there could be some complications with the treatment. For example, it's quite painful and becomes harder to administer, making it more likely to fail. There's also the possibility of scoliosis in the future too, and this could bring about further issues.
But there is the possibility of a one-off treatment called zolgensma. It was originally licenced for children up to 12 months, meaning Tilly wasn't eligible.
Her parents are waiting to see if this may be something she can have in the future.
While it's a positive step, it's hoped that there will be a cure one day, instead of a treatment that just halts the disease. That being said, the options now are a far cry from when Tilly was first diagnosed.
Due to her condition, Tilly needs constant 24 hour care.
She also has chest physio every day and hydrotherapy, which Tilly enjoys every other week, and is vital to help her muscles.
Both Emily and Rob are also offered respite care for a few hours a week.
"She's needed a lot of support," Emily went on, "but she's a really happy girl.
"She's really brave, bright and sociable."
On May 28, Tilly's family and friends will be embarking on a 30-mile walk from Great Ormond Street to their home in Sawbridgeworth to raise money for the children's hospital and for a new wheelchair for Tilly.
Emily will be joined by her cousin Faye Morgan-Wren and friend Kate Ings, who both helped organise the event, as well as Tilly's granddad Bill, and Emily's friend Laura Smith.
"I feel increasingly hopeful about the future," Mum Emily said.
"I feel hopeful for patients with SMA, and I think advancements in treatments really are changing the face of the disease.
"I want people to know, and other families who have children with this condition, that there is hope. There's happiness as well as the hard times."
To donate to the family's walk from Great Ormond Street, visit their GoFundMe page here.
