The 12-year-old, whose dad is former Manchester United footballer Dwight Yorke, has Prader-Willi syndrome (PWS), a rare genetic condition.
He is also on the autism spectrum, has limited vision and can't walk far unaided. Every day, he has to take six types of life-saving medication.
Mum-of-five Katie, 36, went on This Morning with her oldest son to talk about the challenges of caring for him but said she has the full support of her own mum, Amy Price, 62, who also appeared on the show.
Celebrity Big Brother winner Katie told presenters Eamonn Holmes and Ruth Langsford: "People say 'how do you cope?' but I don't know any different"
She then turned to Harvey and said: "He is hard work, he does play up for mummy sometimes, don't you Harvey?"
Harvey cheekily replied" "Yeah, babe."
Katie said one of her biggest challenges is controlling Harvey's hunger because a symptom of his condition is a constant desire to eat.
She said: "He just wants to eat, eat, eat and if we're not looking he will steal food.
"He's a big boy because of his thyroid and with Prader-Willi everything is about food."
As he approaches his teenage years, Katie said – despite the challenges - Harvey is a delight to be with.
He loves to play instruments like the piano and drums and to draw.
And he produced a picture he had made especially for Eamonn and Ruth during his appearance on the ITV show.
- Katie Price (@MissKatiePrice) March 13, 2015
He told them that he loves listening to music and his favourite song is Adele's Skyfall.Katie's mum Amy said: "He doesn't have to use a braille machine which is a real bonus because we never thought he would be able to see, let alone be able to read."
Katie also said she gets a lot of support from her husband Kieran Hayler, 27.
She said: "He is so good with him."
The couple have reconciled after Kieran cheated on Katie last year while she was pregnant with his daughter, Bunny, who was born last August.
They also have a son, Jett, 19 months, while Katie has also two children with ex-husband Peter Andre, Princess, nine, and Junior, seven, as well as Harvey.
More on Parentdish: Katie Price and Katie Hopkins compete for Celebrity Mum of the Year 2015