Gwendoline Riley readily admits that her need to write borders on the obsessive. "Definitely," she says, eyes lowered as though revealing some intimate secret. "I can't muster the energy to engage with any other thing, so thank God I can do this." She gives a short, brittle laugh. "Because, if I had to go without it, it would be very depressing trying to do other stuff… I mean, I can't forge a new career from scratch at this point."

Luckily, there is no need for her to do so. At the age of 33, Riley has just published Opposed Positions, her fourth book. Written in the first person, it tells the story of Aislinn Kelly, a 30-year-old occasional novelist, beset by both financial and emotional insecurity and plagued by what one reviewer has accurately described as "one of the most convincingly monstrous fathers in contemporary novels".

When we meet in a restaurant near Riley's Shepherd's Bush home, she concedes that her protagonists are always fairly similar to her. "I've tried writing in the third person," she says. "I can't do it – it always sounds so false." What about writing as a male narrator? Riley gives a semi-comic shudder. "Ugh, men's brains! That vipers' nest? No."

Opposed Positions took her four years to complete – it was, she says, by far and away the most difficult book she's written, partly because much of it was based loosely on personal experience.

Perhaps for this reason Riley seems to approach the interview process with deep suspicion. For the first 10 minutes after we meet, she is uneasy and scratches at her arm as she answers a question. When I tell her how much I loved the book, she smiles awkwardly. "I feel all wrong-footed now." Riley orders a gin and slimline tonic. Drinking it seems to relax her.

The nervousness is rather endearing given Riley's litany of achievements. Her debut book, Cold Water, was published when she was 22 and won a Betty Trask Award for first-time novelists. Joshua Spassky, her third, won the Somerset Maugham Award in 2008. A volume of short stories, Tuesday Nights and Wednesday Mornings, appeared along the way. Her writing has been compared to F Scott Fitzgerald, Carson McCullers, Virginia Woolf and Albert Camus. Riley's precocity would no doubt be irritating were her talent not so extraordinary. Anne Enright gave Opposed Positions a rave review in the Guardian and concluded that Riley was "more than up to the job of writing the wasted hinterlands of the human heart".

Did that please her? A rapid nod of the head. "I really liked The Gathering [the novel for which Enright won the Man Booker in 2007]. I'm definitely into that whole family-imploding-into-a-horrible-black-hole thing."

In Opposed Positions, both the family and the black hole are skilfully managed. At times, Riley's prose is so psychologically exact, so brilliantly attuned to the smallest gradations in atmosphere and tension, that reading it is almost physically painful. The portraits of Aislinn's disconnected mother, her bullying, manipulative father and her passive-aggressive, tuba-playing stepfather are brilliantly done. Does she really hate the tuba so much? "Oh yes. There've been a lot of times when an argument's been going on, accompanied by the sound of tuba-playing next door," she replies.

A fair amount of real-life experience has gone into the writing, she says, though she's unwilling to go into details. But, as with Aislinn, her parents divorced when she was young and her mother took her and her younger brother to live with Riley's maternal grandparents in the Wirral.

"It was horrible," she says baldly. Writing became a retreat and the young Riley was forever making up short stories. "I liked the privacy of it, I suppose." In fact, it never occurred to her to do anything else with her life. When pressed to explain where this drive came from, Riley is unsure. "I didn't have much of a family. I don't see my dad. My mum… I couldn't tell you what she thinks. No one was there going, 'Follow your dream!'"

She doesn't want children of her own, she says. Why? "Philip Larkin wrote a poem about it didn't he? For that reason. Because the buck stops here. Because I've got bad blood. Because what would a child do with themselves? It's too difficult."

Riley ended up doing a degree in English literature at Manchester Metropolitan University. "I loved it, it was fantastic," she says. "I remember writing essays and waking up in the middle of the night with ideas and wanting to write them down." She graduated with a 2:1 and became literary editor for a brief time at Manchester's local magazine, CityLife. After that, she worked on and off in a bar for eight years while she wrote, eking out a living on literary grants when she couldn't make ends meet.

In her 20s, Riley enjoyed several brief spells in America, a place where she found it easier to think and write – Joshua Spassky was set in Asheville, the North Carolina town where Zelda Fitzgerald was killed in a fire. "I just needed to be on a different continent," Riley says. "It's not an original idea. I just found being 3-5,000 miles away from everything was better."

These days, having moved from Manchester to London, Riley still writes full-time, getting up in the mornings, sitting down at her computer – "One of those netbooks that look like sandwich toasters" – and not moving until her inspiration has dried up. She does not own a television or a radio and is a fervent note-taker. "If something strikes me, I have to get it down, otherwise you lose it… I know, having done this for a while now, that I'm terribly slow. It takes me a long time to get anything together… To begin with, it's all a bit haphazard. There's no plot, no characters or anything. I just see what catches fire."

Her inspirations come in varied forms – she's a die-hard Morrissey fan and counts Fitzgerald, JD Salinger, Philip Roth and Alice Munro among her favourite authors. Indeed, she has unapologetically high literary standards. "Someone told me I should read HHhH [the debut of French author Laurent Binet] recently," Riley says. "I thought it was absolute bollocks."

Riley is already working on her fifth novel, despite being in her early 30s. Does she feel young, I wonder. She laughs, her face clearing. "No, I don't feel particularly young. I used to feel a lot more gauche than I do now. I used to feel very embarrassed – not knowing how to act or what to wear. I was constantly out of my depth."

And now? She grins. "I feel a little less at sea."