Drinking too much, regretting the things you do when you drink too much, struggling to find your place or make a living in an unforgiving city – for many of us, this is what twentysomething life is. Christ, it's what thirtysomething life is. It was what life was like for Amy Liptrot, apart from one key distinction – drink came to obliterate everything else.

"I would see other people who drank with the same urgency as I did and I knew they were like me," Litptrot tells me. "It wasn't just a part of the social life – it was the driving force."

It's also the driving force behind her new memoir, The Outrun, in which Litptrot unflinchingly recounts her descent into dipsomania and subsequent recovery on a remote Scottish island.

Liptrot grew up on a farm in Orkney – an archipelago of islands off the northeastern coast of Scotland – escaping south to Edinburgh to go to university and continuing south until she reached the bright lights and dirty streets of London. Her childhood was unique, but her anecdotes of being 23 and living in east London are the same as yours. The lunchtime tinnies in the park that turn into a boozy dinner in a restaurant, warehouse parties until dawn, Sundays spent inert with a hangover.

But then Liptrot's story unfolds in a different way; her tales of drinking and drunkenness become less relatable. They turn into stories of losing jobs, of being arrested for drunk driving, of physical seizures, of being badly assaulted in the back of a stranger's car – and then, at thirty, of being in rehab, living alone in a bedsit above a pub in Hackney. "I heard it said that in London you're always looking for either a job, a house or a lover," Amy writes. "I did not realise how easily and fast I could lose all three."

Alcoholism is a big word, and one which means different things to different people. We bandy it about as an ironic joke, or whisper it, concerned. We don't utter it at all, when perhaps we should. Even now, five years sober, with a book about her drinking and subsequent rehabilitation just published, I sense the word is not an easy one for either of us to say.

"There's a trajectory with alcoholism," Liptrot tells me over a cup of tea in east London, not far from the old life she lays bare in her book. "At first you're being a dick to your friends and then your friends don't want to be your friends anymore. And then it comes to things like losing your job, losing relationships, leaving a birthday party early to go home by yourself so you can drink at a faster rate.

"I first went to an AA meeting about four or five years before I went into rehab," Liptrot continues. "People were telling me I had a problem and like a lot of other alcoholics, I had to go through a whole process of battling against it and attempting to control my drinking and failing. I would finish work, go to the shop and think 'I'm going to have two cans of beer' and then be in there again a couple of hours later buying four more cans. That was hundreds of occasions."

It's this feeling of not being in control of drinking which many would say is a signal of alcoholism. Sarah Hepola, whose memoir Blackout is about her own struggle with alcohol, told me a similar thing.

"I would say I'm only going to have three drinks at this party, but I would have ten. Or I would say I'm not going to drink this week but I'd drink on Tuesday," Hepola says. "For me, there's a lot of key phrases that identify alcoholism, but one of the key ones is 'I can't stop'. When you want to stop and you can't. That's when you need to realise there's a problem."

For Lucy Rocca, whose documentary My name is… and I'm an Alcoholic came out earlier this month, others might not think there's a problem, but you do. Writing in The Guardian about her decision to get sober, she said: "There were too many mornings when I woke up and despised myself for something I’d said or done the night before when under the influence; too many blackouts that scared me to death, whole nights disappearing into a fog of alcohol-induced blankness."

"Sometimes I do feel like I need to prove my drinking was bad enough", says Liptrot. "I've met people in London who maybe thought I was never that bad, but then they never knew what was going on when I got home."

One day, something snapped and Liptrot made a call to her boss, quit her job and went into rehab. "The game was up for me. I was deliberately drinking the next day to suppress the memories of what I'd done the night before."

Indeed, it was only once Liptrot was back in Orkney, living alone on Papa Westray – a tiny island with a population of 70 – to continue her rehabilitation that she realised "opting for rehab and total sobriety was not an overreaction to my situation."

And here is the second story of the book – the story of Liptrot leaving London to return to the farm she once longed to escape, getting under the skin of the island, living alone in a cottage with just her laptop for company, and crucially, staying sober.

"The bits about being drunk and the things that happened to me at that time are a small part of the book," Liptrot says. "Really it's about what happens to you after you stop drinking, finding a new lifestyle and allowing the unexpected to happen."

The unexpected for Liptrot was immersing herself in island life, and coming to appreciate its beauty: she took a job with the RSPB which would see her scour the island at night in search of a rare bird, the corncrake. She swam in the sea with strangers. She built dykes (stone walls) with her father. She walked. And she wrote her book.

"When I started writing it, it was from a place of desperation really – I had nothing else going on. But the writing itself has been as important in my recovery as the 12 steps or the sea swimming and bird watching. I didn't know what would happen when I changed my life, but I had to allow myself the opportunity to find out."

The Outrun by Amy Liptrot, published by Canongate Books is out now.