Her attempt was denied because concerns about her haemoglobin levels and low blood pressure, and she was told try again a month later.
"I was just looking forward to doing something good, but with the pre-check ups they found my red blood cells was quite low, so we just put it down to that I didn't drink enough water," Ms Trinh said.
After getting the same results the second time round, real concern was raised on her third try when the lab results urged Ms Trinh to contact her doctor for a full-count blood test.
"It showed that I had high levels of ferritin, which is really odd for an Asian — also really odd for a female," she said.
The busy working mother admitted she waited a full month to visit her doctor but once she did within five hours she was rushed to the emergency ward and diagnosed with an acute myeloid leukemia.
"It had been in body for about two weeks and in 50 per cent of my blood stream, if I had gone undiagnosed, I would've been dead within four months," she said.
"I thought I was going to die, the first thought in my mind was to prepare my funeral and to prepare my family to live without me."
Red Cross Blood Service spokesman Wes Thomas said donating blood acts as a "mini free health check".
As Queensland enters flu season, blood donations dwindle as regular donors fall ill and demand from hospitals across the state rises.
"Queenslanders contribute just over 21 per cent of Australia's blood supply, but as a nation only one in 30 people donates, while one in three people needs a blood donation, said Mr Thomas
"Thirty per cent of what we get goes to cancer patients because of their ongoing transfusions," he said.
The donor becomes the recipient
After undergoing intensive chemotherapy sessions, Ms Trinh's body was depleted of platelets and required 20 bags of blood just to stabilise.
"I was knocking on death's door and the only way to save me was through blood transfusions," she said.
That was not enough when the cancer returned for a second time over two years later, which meant instead of blood donations Ms Trinh needed a stem cell transplant with her exact body match.
"I won't forget the day I found out, I cried and cried," she said.
"My brother was the perfect match for the stem cell transplant; the process was so much longer with chemo and radiation therapy, and it affects you for the rest of your life.
"I had to thank the man upstairs for looking after me, I feel so blessed I beat leukemia twice."
Even though she is unable to donate, Ms Trinh wants to educate the next generation to be aware of what they can do to save lives.
"Be a hero, trying to give blood actually ended up saving my life."