Yet she is still a child herself, thrown into the role of head of the household at the age of just six after her mother died of AIDS.
Nirmala, now 15, has never been to school, never learned to read and write, and never had the sort of childhood enjoyed by her friends whose shouts of excitement drift into her home as they play outside.
"If I don't go out all day to collect firewood to sell, there is no food to eat. I have to work or my brother and sister will have empty stomachs," she says. "I also do everything around the house -- all the cooking and cleaning."
Nirmala rises at first light, makes sure her 13-year-old sister Sita and 10-year-old brother Suresh are fed and washed and then heads out for work.
She spends all day collecting piles of wood in the forests below her tiny, mud and clay home in Biraltoli, a hamlet high in the hills an hour's walk from Mangalsen, the main town in western Nepal's impoverished Achham district.
The money she earns -- 100 rupees ($1.20) on a good day -- means Sita and Suresh are able to go to school, enjoying opportunities she will never have.
"I'd like to play but if I spend time playing it means we don't eat," she says.
Nirmala's father, a migrant labourer working in Mumbai, infected her mother with HIV on one of his visits home. He eventually died of an AIDS-related illness while he was in India.
Nirmala's story is all too common in remote Achham, one of the poorest regions in South Asia where health infrastructure was ravaged by a decade-long civil war that ended in 2006.
Jobs are scarce and up to half of the young male population travel abroad -- primarily to India -- to find work.
"Because of a lack of education they have unprotected sex with sex workers and contract HIV/AIDS, which they bring back to Achham. It's a huge problem," said Sharmila Shah, a UNICEF-funded village facilitator.
The humanitarian organisation estimates that some 13,000 children have lost both parents to an HIV/AIDS epidemic sweeping Nepal's rural communities, up to 1,500 of them in Achham.
Bikram Augi, 17, cooks rotis for his 14-year-old sister Pashupati's breakfast before leaving the mud and brick home they share high in the hills above Sanfebagar, a township of tin-roofed shacks lining the Budhi Ganga river.
He became head of his household at the age of nine when his mother, who was 32, died of AIDS-related illnesses.
"I went to school that day. I remember it was a Friday which meant we had a half day. I came home and my mum looked like she was coming to the end," Bikram tells AFP.
"My sister and a neighbour were at home with my mother. When mum saw me she said: 'This is my end time -- look after your sister and take care of yourself.'
"I started to cry, and within 10 minutes of saying that to me she was dead."
Bikram found out through relatives a year later his father had also died, in Pune, India. He says at least 20 of his friends are also AIDS orphans.
"From the day my mother died I have had to collect wood from the forest and bring it home. I've had to cook and clean and look after my sister," he says.
"Even when I was nine, I'd work the whole day and when I got home I'd go to bed and cry most of the night for my parents."
UNICEF and local charities have helped Bikram by providing school clothes, mattresses and food, allowing him to quit his job two years ago and attend his school, 90 minutes walk away.
He is positive about the future and wants to pass his exams so that he can help educate others on the dangers of unprotected sex.
But he is part a depressing cycle that shows no signs of being broken.
Dhunki Nepali, 30, sits outside her ramshackle clay and stone home near Mangalsen cradling the toddler she knows she will probably never see grow up.
She has been living with HIV since her husband infected her about 10 years ago.
Dhunki's youngest children, two-year-old Rajesh and his four-year-old sister Yamshara, are undergoing tests and are yet to get the all-clear. But her eldest boy, Harka, nine, is HIV positive.
She has not seen or heard from her husband since he went back to work in Mumbai soon after her positive test and does not know if he has been tested for HIV.
Dhunki and Harka are receiving anti-retroviral drugs provided by the government but she says she is becoming increasingly ill.
"I'm starting to feel tired a lot and I'm suffering from a lot of mild fevers.
"I'm taking medicine which I'm being given by the government but I'm worried that I will die and my children will be alone."