Miss Hirovanaa never got to a school ball that year, didn't finish high school and can't remember anything that happened in 2014 or 2013.
"I basically lost two years of my life. I had to go to rehab to learn to walk again and my speech had been affected as well so I had to relearn how to say some things," she told the Herald.
"All my friends moved on from teenagehood to adulthood but I wasn't able to. My twin sister went to three school balls that year and was able to focus on university, and do everything I'd love to do."
Doctors believe the initial seizures were caused by an unknown virus attacking her auto-immune system but she hasn't been given a definitive diagnosis.
"It's frustrating not knowing why they happen or when they're going to.
"I'm not able to go anywhere by myself because when I have a seizure my body goes numb and I have to hold on to someone and sometimes be carried then I need to sleep for about three or four hours.
"On bad days, I have to stay in bed all day."
Despite everything, the teenager has started university this year -- but it's not without challenges.
"I had my first seizure at university the other day. My friends called the ambulance because they were worried about me.
"I still have trouble remembering things so my friends message me what homework we were given in class.
"It takes up all my energy most days so I'm not really able to do much else. I really miss sport, especially netball, but I don't have enough energy to play it anymore."
Miss Hirovanaa will take part in International Purple Day for epilepsy on March 26, where she hopes to meet other young people with epilepsy.
She is also hoping to get an assistance dog to curb her "craving" for independence.
* Epilepsy New Zealand is encouraging people to wear purple or host purple-themed events for International Purple Day on March 26 to raise funds and awareness for the about 90,000 people in the country who have the condition.
Go to epilepsy.org.nz for more information.
