But amazingly tiny Faith is aged seven - a year OLDER than her bigger sister Hope, who is only six.
Little Faith has an extremely rare form of dwarfism, with only 30 cases reported world-wide.
It means that her younger sister, Hope towers above her - and strangers always think that Faith is the youngest sister.
She only weighs the same as an 18 month toddler and her school uniform is aged three, and has to be specially altered.
Faith's mum, Mrs Findlay, 40, a nanny, says: "Her condition was so rare it took doctors years to find out what was wrong with her. She may be tiny but she has such a big heart. And she loves being small.
"She tells me that she doesn't want to be bigger. All good things come in small packages - and that's what Faith is."
Ironically when Faith was born, she was a normal weight for an average baby, weighing 8lb, 1oz, and she was the heaviest of the couple's three children.
Faith's older sister, Grace, now nine, weighed in at a smaller 5lb, 6oz, and her younger sister, Hope weighed 6lb, 13oz when she was born.
But by the age of three months, Faith was constantly being sick and had recurrent coughs and chest infections.
"We never thought there was anything wrong with Faith when she was born - she seemed just perfect," explains her mum.
"But then when she was just a few months old, she started being poorly all the time. She just seemed to pick up infections one after the other."
When Faith was 11 months old, she suddenly started gasping for breath and her mum and dad rushed her into hospital.
She was placed on a ventilator and doctors discovered that her lungs were full of fluid. Tests showed that she had an abnormal heart valve that was leaking directly into her lungs.
"She looked so frail lying there and we didn't know what was wrong," recalls her mum. "She still weighed only 11Ibs, and she'd had her first birthday. We couldn't understand why she was only so tiny.
"The doctors thought at first that the leaking valve had caused problems with her digestive system which had restricted her growth."
Faith then underwent a nine hour operation to replace her faulty heart valve with a mechanical one. The operation was a success, but as the months went by she still didn't grow, as her mum explains:
"People used to think she was so cute because she was so tiny, but by her second birthday, she was still no bigger than she had been at her first birthday.
"She seemed too little. When her sister Hope reached her first birthday, she was the same size as Faith. People used to think they were twins."
Faith was referred to a genetics centre in Newcastle who found that she was producing growth hormones normally. All the tests for growth conditions were negative.
When she started school at the age of four, the school had to fit extra steps in the classroom and she had a booster seat to be able to sit down for mealtimes.
Then doctors finally discovered an answer. Tests showed that Faith had a condition called Geleophysic Dysplasia, an incredibly rare form of dwarfism.
It is caused by inherited genetic mutations which result in very short stature and abnormalities to the bones, joints, heart and skin. Unlike many forms of dwarfism is doesn't cause shortened limbs - just a miniature frame.
It can also cause abnormalities to the heart and an enlarged liver. It is often life threatening, but sufferers can live in to adulthood.
"We were absolutely devastated when Faith was diagnosed," says Mrs. Findlay.
"We had never even heard of this condition before. The chances of her having it were a staggering 200 million to one. She had just been incredibly unlucky."
The couple's other two children were tested clear of the condition, and there is no cure for Faith, who has been the subject of a medical journal in Newcastle.
She has had another two heart operations and her chest cavity is now struggling to hold her growing organs:
"She has been in hospital recently because she was struggling to breathe. Her organs are getting squashed in her chest, so we don't know what the future holds for her.
"But she is just taking one day at a time. She may be tiny, but she has the heart of a lion. She's so fearless and feisty - if she thinks her younger sister is being picked on, she'll stand up to anyone.
"She's full of fun and says she wants to be a princess when she grows up. She's an absolute mini marvel and a real inspiration."
What an absolute star, good luck Faith!