She has been called a traitor by her former coach Vladimir Kazarin and is currently in hiding in North America with her husband Vitaly, a former Russian anti-doping official.
"In 2007, for the first time my coach (Kazarin) started giving me testosterone injections," she told the BBC in an interview.
"I did know it was banned, but before giving it to me I think my coach prepared me well because he was telling me stories about how it's normal, that's how it's done.
"Every night I had a dream that the doping inspectors were coming to test us, every single night the same nightmare. I was really afraid of being tested because I didn't know how the system worked.
"I didn't realise that the management was in on it, that even if you're caught you won't be disqualified if your coach has connections."
Stepanova, who was given a two-year ban in 2013 for abnormalities in her blood passport, said that suspension made her determined to expose how deep the problems in Russian athletics had actually spread.
"It was a turning-point and I had a choice or rather a second chance," she added.
"I could return to the same system and simply think, okay so they're lying, but they'll take me back into the national team and pay me money or else I could do the right thing."
She spent the next two years gathering evidence, driven by the desire to expose the truth.
"The reason I was doing it was to show that this was the system," she said.
"I just wanted them to admit that yes, everyone's doing drugs, the bosses are covering it up. That's what was important to me."
Stepanova said she thought telling the truth would make things better.
"I don't consider myself a traitor," she said. "I simply revealed the shameful truth, which our country doesn't want to confront, and the only reason I told the truth about it all, was to try and put a stop to it."
(Reporting by Simon Jennings in Bengaluru, editing by Ed Osmond)
