"I wasn't able to be a typical 18 year old," she tells this week's Star magazine, "You have to grow up very quickly because you can't be a kid any more. You can't be silly or get drunk or stay out."
Her parents, she says, 'weren't chuffed' when she announced her first pregnancy. "My dad was very upset to be honest. He thought I would give up my dreams of my career and then when he realised I wasn't going to do that he was behind me a million per cent."
Now a mum of three - David 16, Emily, 14, from her relationship with Dave Cunliffe, and nine-month-old baby Polly with partner Jamie Lomas - Kym says the documentary reminded her of just how much she worried about finances as a young mum and how some people judge girls who get pregnant, claiming they do it because they 'just want a council house'.
"I had it quite easy compared to some because there are some girls who don't have families to support them. Or they didn't have the fathers around. But I had Dave; (the father of her two eldest children, David and Emily) he was completely involved and still is."
"There was a girl [on the documentary] who moved herself away from her family so she could learn to be a decent mother. I saw how much she was struggling and so when people judge her in the street and think, 'They just want a council house' I know that the reality is very different."
Kym says she was motivated to make the programme because of the stigma attached to teen mothers and the perception that they want to live off benefits, and also because she wanted to see how things had changed since she was 18. She says she found the disapproval of teen mums had got worse, and that it was something she 'didn't feel' as a young mum as much as some of the girls she met.
And having gone through teenage pregnancy, her answer to reducing the number of teen pregnancies in Britain is more sex education. "Maybe we need to talk about sex education even younger and delve into it even more," she says, "And at home as parents we need to have more open conversations. I'm very open with my kids and they do get a bit 'Oh mum!'. My son is 16 so I am having those conversations all the time and he's very embarrassed by that but it's important."
Kym is also emphatic that she does not want her eldest daughter Emily to be a mum as young as she was. "I don't want Emily to get pregnant at 18. It's hard work. It's not what I want for her. I'd be devastated but obviously I would completely support her. If my parents hadn't been there for me I don't know what I would have done."
Read the full story in this week's Star magazine - out today