He has revealed that this is the first time in the last eight years that he has managed to stay off drugs for such a long time.
The Babyshambles frontman also told BBC Radio 4's Front Row programme he has been reconciled with his estranged father after three years apart.
He is now living in Wiltshire after spending time in a rehab centre there.
"In the last eight years, I've never been that long without drugs. I'm not going to lie and say it's not a struggle, because it is. But in a way, I'm quite proud to be able to admit it, particularly for my mum and dad," the BBC quoted him as telling Radio 4's Front Row programme's presenter John Wilson.
"I'm quietly confident, but there's an underdog feeling about it still. These last few months have been a turning point," he added.
The 28-year-old singer faces sentencing for drug and motoring offences later this month. He has already admitted to driving illegally in May while in possession of crack cocaine, heroin, ketamine and cannabis.
The hearing at West London Magistrates' Court was delayed to 26 October, so that the singer could complete his six weeks of treatment at Clouds House, East Knoyle.
Doherty's treatment included family therapy, which helped him reunite with his father, Army officer Peter.
"My dad has welcomed me back into the fold. I can actually go home, I can actually talk to him. He came in for some family therapy, which is a miracle in itself. It was an emotional time, to be honest," he said.
Doherty also revealed that as part of his treatment, he was allowed to play the guitar twice a week.