She grew to love her time of the month, saying it's "beautiful and powerful", and wanted to share her new appreciation with women around the world.
She started collecting her blood and one day had an "impulse" to smear it across her face and share photos online.
She said: "We hold so much shame in our bodies, and most of us do not realise it until we intentionally explore it. Our periods are an incredibly magical time of month that holds immense power, and our society keeps us away from that as much as possible.
"I am endlessly fascinated by my body and its patterns. Many people talk about the parts of the cycle being like the seasons, with the energy of ovulation being like summer, and the energy of menstruation being like winter. I think that's generally true, but I've also found it's very individual.
"Sharing pictures of blood on my face and body was just an impulse I was creating a series to help women connect with their menstrual cycle, and I thought it would be fun. We can also do things like paint with it or pour it into the earth. I believe it's a beautiful thing to get comfortable with touching your own blood.
"There is a tremendous amount of power in learning that we can experience pleasure from the parts of our bodies we deem in society as 'disgusting'. If we can love the unlovable, all of life opens up to us. We spend a lot of time learning to control our bodies; instead I believe in learning from our bodies.
"My blood to me has become fun, beautiful, and powerful, and playing with it brings me closer to myself."
Demetra, who lives in Los Angeles and works as a s-x coach, had her first period when she was 12.