Katie - who has undergone more than 100 operations to rebuild her face after a horrific acid attack in 2008 - also told how her outlook on life has changed.
"To have had my own life saved in hospital and then to be there giving life to this precious little person, I thought, 'This is why, this is what it's all about.'
"I already felt grateful that I'd managed to restore a life, and I thought, 'You can't expect to have everything, this is enough'.
"I thought I knew, after all that happened to me, what happiness meant, but having Belle has shown me what true fulfilment is."
The full interview is the new edition of Hello! which is out now.
LOVE KATIE? Hear more from the new mum in the video below...