Bianca Innes, 21, from Queensland, Australia, first found a small lump inside her breast this March and was told by doctors that it was likely to be a cyst.
But after it tripled in size and became painful, tests revealed it was cancer.
The student was devastated and told she needed chemotherapy followed by surgery to save her life.
Bianca was just eight weeks from celebrating her 21st birthday and was forced to cancel her plans, spending the day in her hospital bed.
But now just eight weeks since being diagnosed, Bianca is sharing her story in a bid to raise awareness for young women with breast cancer.
Bianca Said: "I wasn't worried about the lump at first but when it tripled in size, I knew something wasn't right so I had an ultrasound and a biopsy to rule out cancer.
"I kept thinking to myself 'how am I going to do this?'
"I wasn't going to watch my hair fall out and be depressed about it, in my fourth week of chemo my hair was falling out in handfuls."
Losing her dark brown hair has been the hardest part of Bianca's cancer ordeal so far.
Bianca added: "I just balled my eyes out, losing my hair was hard, it was really difficult."
Bianca now wants to raise awareness for the next girl who is 20 years old and has breast cancer.
She said: "If it's me this year, it's going to be someone else next year.
"Only one 20-year-old woman will be diagnosed with breast cancer per year, and I was that unlucky one this year.
"I started writing my blog as an outlet for myself and when I noticed people were reading it, I thought to myself, maybe I can raise awareness for that one girl that will be in her twenties and have breast cancer next year."
Bianca was carefree before her breast cancer diagnosis and never imagined she'd be battling the 'Big C' so young.
She said: "Last year everything was so normal, I loved going to the gym and I was really fit and healthy.
"I spent time with my friends and did everything a normal 20-year-old girl would do. One year later I have breast cancer, I didn't see it coming."
Bianca is now aiming to raise awareness for younger women to check their breasts and get regular mammograms.
Bianca said: "There's times you think that you can't do it but I just look at everything as a phase, just get through this one thing first.
"I never knew that I had this much love and support around me, I've never once felt alone going through this."
A spokesman for the Australian Government Department of Health said: "Breast cancer is very rare in women aged 20.
"The latest data on breast cancer incidence, reported by the Australian Institute of Health and Welfare, shows that in 2013, a total of five women aged 20-24 years were diagnosed with breast cancer.
"As screening mammograms are not suitable for younger women it is important that younger women are aware of the usual look and feel of their breasts. They are advised to look out for the following changes:
A new lump or lumpiness in your breasts, especially if it is in only one breast.
A change in the size and shape of your breast
A change to the nipple such as crusting, an ulcer, redness or the nipple pulled in
A change in the skin of your breast such as redness or dimpling or puckered skin