Kirstie was already on the transplant waiting list and had been told that she only had six months to live.
The documentary starts with Kirstie and her fiancé Stuart three weeks before their wedding day and although Kirstie was living at home at the time, she was on oxygen machines 24 hours a day to help her breathe, confined to a wheelchair and having constant IV's and pain medication.
She was barely able to stand for a couple of minutes let alone plan a wedding.
Our whole crew consisted of an assistant producer and me - during the ten weeks of filming, this amazing young couple battled everything to live their life to the full.
We followed Kirstie being hospitalised and fighting for her life two days before her wedding, even checking herself out of hospital early to make it down the aisle.
A couple of weeks after the wedding you'll see how Kirstie was still so thrilled to finally be married before the sudden shock of having to be taken by air ambulance to the transplant hospital in London, knowing that if she didn't get there right then, she would never survive the journey.
It was an extremely emotional time in this couple's life that as a filmmaker I couldn't help but be affected by.
Each time I filmed with Kirstie I was acutely aware that this could be the last time I would ever see her alive again.
Watching Stu talk about how it felt to be in a situation where the person you love is dying and there is nothing you can do to save them, is something I'll never forget.
Kirstie's husband Stuart waits for news
Filming with Kirstie and her family when they were going through such a painful and highly emotional time put me in an unusual situation but I was very privileged to be able to follow their journey and they were extremely supportive.
Her drive and determination made it much easier to talk openly about difficult issues such as death and living with illness.
Choosing the music for the film was always going to be an extremely important element for me to help add a layer of emotion and try to reflect what everyone was feeling.
Throughout filming, I was constantly listening to albums and almost creating a soundtrack in my head as I saw the events unfold in front of me.
In the edit I found that if a track made me completely re-live the moment then that was the right one to use.
I quite often wouldn't listen out for relevant lyrics but literally watched through footage with headphones permanently attached and when a track had absolutely the right feel to it I would play it back and realise that actually the lyrics added to the scene.