LOS ANGELES – In her Beatlemania schoolgirl outfit – gray miniskirt, knee-highs and electric-blue suede shoes – Tavi Gevinson looks like any other fashion-obsessed teen as she wanders the crowded aisles of Los Angeles’ American Rag Cie.

“I can’t afford, like, anything here on my allowance,” the 17-year-old said, scanning the store’s horizon for any gems she might have missed.

She pulls out her iPhone and responds to a text.

“My dad, he’ll be here in about half an hour to pick me up,” she said, heading toward a carousel rack of vintage-image postcards – “the one thing I actually can afford!”

Tavi is decisive as she plucks out certain moody postcards and quickly discards others. When the wobbly rack catches on the carpet and fails to turn, the petite Tavi lifts the metal display and firmly plants it a few inches away, where it swirls freely.

“There” she said sweetly. “I’ll take these four.” After paying, Tavi tucks the cards away in her floral backpack. “Now, what were we talking about again?”

One can forgive the high school senior for being a bit distracted. After flying in from Chicago, she was up late the night before finishing an essay. But the assignment wasn’t for school. It was the editor’s letter for Rookie, the online pop-culture magazine she started when she was 15; now she oversees a staff of about 80. There was also a photo shoot this morning, followed by a meeting with her agent and then another whirlwind shopping trip in Hollywood.

She will appear at Skylight Books later to sign copies of “Rookie Yearbook Two,” an annual print anthology of Rookie’s best online writing paired with original content from the likes of Lena Dunham, Mindy Kaling, Judy Blume and singer-songwriter Grimes. The store expects an adoring mob of teenage fans for Tavi, called “the future of journalism” by no less than Lady Gaga.

Part Tina Brown, part Dorothy Parker, the quick-witted Tavi has the ear – and Tumblr accounts – of a new generation of young women. Not to mention the eye of the media, the fashion world and, lately, Hollywood filmmakers.

She was just 11 when she started the Style Rookie fashion blog out of her Oak Park, Ill., bedroom. Soon she was sitting on the front lines of New York’s Fashion Week. Fast-forward to 2013: appearances on “Late Night With Jimmy Fallon” and “The Colbert Report,” international speaking engagements and a role in the film “Enough Said” opposite Julia Louis-Dreyfus.

With more than 4 million page views a month, Rookie is emerging as a DIY multiplatform media empire of sorts for Girl America.

“I’d felt like there wasn’t a publication for teenagers that was respected. Or that I, myself, or my friends could really relate to,” Tavi said, settling into a booth at the cafe next door to American Rag, her creamy skin, crimson lipstick and blond bob giving her something of a “Ghost World”-era Scarlett Johansson quality. She slurps her lemonade.

“One thing I’m very proud of is that Rookie has a lot of legitimacy in publishing and music journalism and fashion. As it’s grown, the goal has become more to make people feel included, that they’re cool enough or smart enough.”

How is she able to ingest so much pop culture daily, interview her heroes, blog prolifically, write essays for Rookie and oversee her staff – all while attending high school? It’s simple time management, she said..

Tavi spends nearly every sliver of downtime listening to podcasts or music – most recently Lorde, Taylor Swift and Kanye West – while walking to school, for example, or watching old episodes of “Freaks and Geeks” and “My So-Called Life” at night. Study hall, she says, is a perfect time to read other books she finds more relevant in the long run, like “Girl Power” by Marisa Meltzer.

Such efficiency, however, is not without sacrifice.

“There are compromises,” Tavi said. “Like there have been times when my grades have suffered or I can’t visit my boyfriend when I’d like to because I have a number of interviews that day. But it’s worth it.”

Still, Tavi’s parents have made sure to keep her life “full of normal teenage stuff,” said her father, Steve. She attends the local public high school and recently got an allowance increase. She doesn’t yet earn a salary from Rookie – though that may change soon, he says, as the site becomes more profitable – and speaking engagement fees go into her savings. The total sum of her liquid assets from day to day is her allowance: $25 a week.

“It’s a nice little fiction that we’re living out because she has this bank account,” he said. “But she likes living that way. We like her living that way.”

Like many proud “pop culture nerds,” Tavi has a not-so-subtle obsessive streak. She might get up at 3 a.m. to rearrange all her books, she said, and not only journals her life’s every happening, from monumental to mundane, but also “curates” her peripheral pop culture experiences to match her moods.

“Sophomore year I had my heart broken by a boy. I loved the feeling of heartbreak with dressing in nightgowns from the ’70s, lighting candles and listening to Heart and Carole King,” she said. “I documented it all. It’s like making a bunch of little movies. It makes me feel like I’m in control.”

These days, Tavi’s mood is often a mix of excitement and trepidation. She’s awaiting graduation in May and has applied to New York University, Barnard, Brown and Wesleyan – though she’d like to take a year off first to live in New York and focus on Rookie as well as other creative ventures, such as acting.

“I just hate ‘voice of a generation’ stuff,” she said, balking at the suggestion. “You put someone on a pedestal and of course they can’t represent all of feminism or all people their age or whatever.”

And with that, Tavi scurries out to the parking lot to meet her dad, her books and notes for the evening’s reading bundled in her arms.