Leaving university, moving to New York and following her dream as a musician has made for the most daunting year of Mackenzie Scott’s life. “Well, I’m not under my parents’ protective wing any more,” the 22-year-old says, laughing with a hint of satisfaction. “Or their protective bank account.”

Scott's music career had barely begun when it reached a critical juncture in January, following her self-released, self-titled debut album as Torres (her grandfather's surname). At that point the goal was to get her future work reviewed on Pitchfork by early 2014. Instead the influential music site named Torres Best New Music, hailing Scott's stark takes on tricky subjects such as suicide, jealousy and adoption. The knock-on effect was immediate.

A month later Scott was so nervous about her first show in New York that she hit her head on the mic before she’d even begun, averting her eyes with an awkward giggle.

Among those watching was Sharon Van Etten, a singer who could empathise with Scott's jitters. She had moved to New York to kick-start her own career some years ago, building up a series of acclaimed albums and high-profile collaborations, and gradually honing her stage presence.

But as soon as Scott began to sing, Van Etten was taken aback – it was the grungy guitar, the gritty voice, the confidence that appeared from nowhere – and, in time, she became Torres’s biggest cheerleader. “Her lyrics are poetic, confessional – and I hate that word as a songwriter – but they are true,” says Van Etten. “They’re well-crafted songs with amazing lines like, ‘Honey, while you were ashing in your coffee, I was thinking of telling you what you’ve done to me.’ ”

Scott fine-tuned that gift while taking a songwriting degree in Nashville. She’d been writing creatively from a young age – her first poem, written at 10, was about 9/11 – and began to blend those compositions into music. When she was growing up in Macon, Georgia, her family pooled together one Christmas to buy her a black Gibson guitar, just like her teenage idol Joan Jett’s, and its jagged tone felt like the sound she’d been searching for.

Scott’s parents had insisted that she go to university, and although they supported her choice of course they weren’t convinced a degree in music could provide stability. “I think even until the album came out there was an expectation that I’d say, ‘Okay, time to get real,’ ” she says. “But I never did.”

Songwriting school was “a skin-thickening process”. The classes catered more to those who aspired to be professional songwriters than they did to musicians seeking to express themselves. “There was a lot of, ‘This is what makes money; this is what doesn’t.’ They just teach you how to sell it, to be honest – which can be a good thing to know, but it was also a little disgusting when you see how the hitmakers do it . . . They’re pulling at the heart strings, trying every formula there is to sell songs . . . I’m pretty sure I cried more than once in front of the class.”

Faced with songwriting assignments, Scott would procrastinate until the deadlines were hours away, then retreat to dormitory stairwells in the middle of the night with a guitar. “A lot of those times were when the best songs came,” she says. “I think most people would be surprised at what they can create when there’s no other option.”

The resulting songs channelled loneliness, fear of the future and wanting something that never quite arrives. But they also extolled acceptance and a willingness to learn from that self-awareness. “There has to be light and darkness,” she says. “I don’t know what other way there is.”

After accumulating three and a half years’ worth of material, Scott recorded her favourites in live takes over five days, using an understated rock accompaniment that she hoped listeners would find difficult to date. The response has warranted a rerelease of the album, this week, on a wider scale.

So far she has resisted the interest of record labels, mindful of finding the right fit. And as Van Etten has become something of a mentor since that gig in February, Scott has been paying attention, learning how Van Etten handles herself in the industry. But even though her dream has been realised more quickly than she could have anticipated, sometimes the momentum can be something of a struggle.

“I feel like more of my moments are in doubt than not,” she says. “Getting to do what I love is amazing, and I’m grateful for the way it’s happened this year. But every human being struggles. I think there’s a misconception that everything is fine and dandy when someone is getting to do what they love. The existential crises exist regardless. I know that I’m just predisposed to sadness anyway, so I’m not sure my circumstances will ever negate that predisposition.”

Still, she’s 22. It’s early days yet. “I’m not speaking definitively or anything. I’d certainly love to be an individualised, happy adult,” she says with a laugh. “But . . . who knows?”

Torres plays the Sugar Club, Dublin, on Monday