Three months ago, Rimes seemed unstoppable. But family troubles and a poorly received new album have caused growing pains.

It’s Friday, a cool midnight in California’s San Fernando Valley, and a teenage girl is talking about the movies. Not movies she’s seen, mind you. Movies she wants to make.

Her voice is clear and precise and devoid of irony. “I want to be in a feature film,” LeAnn Rimes proclaims, settling into a banquette on her tour bus shortly after completing the first of two sold-out shows at L.A.’s Universal Amphitheater. “We’ve been talking about bringing back A Star Is Born. Something along the lines of a love story that involved my music. A film with an edge.”

Rimes is 15. Earlier today, while millions of American teens were daydreaming about Leo, or flooding cyberspace with mindless chatter, this dough-cheeked diva was holding court at the offices of Creative Artists Agency. Fifteen Hollywood power brokers seated in a conference room listened closely as the Cinderella CEO outlined the do’s and don’ts of her future filmic forays. Ask Rimes who runs such a meeting and she admits, somewhat hesitantly, “I do.”

Her CAA agent, Rod Essig, is quick to agree. “Ninety-five percent of every decision regarding her career is made by LeAnn,” he says. “Whether it’s about touring, TV, books. I talk to her father and manager, but the final decision is hers. LeAnn knows what she’s doing and where she wants to go.”

And where might that be? “I don’t want to play a young teenage girl, because I want to get away from being stuck with an age factor,” she says. “I’m always stuck with that. I want people to look at me for my music, for my talent. And I guess, at that point, for my acting.”

Though she’s still too young to drive, Rimes is America’s fastest-growing brand name. In a stretch of two years she has gone from being a pubescent Patsy Cline clone to a Grammy winner, a Grammy snubbee, an author, an actor, a hawker of milk and cell phones, fodder for Internet gossip, and a mega-platinum showbiz conglomerate. Tally up last year’s record and concert-ticket sales and Rimes churned out profits in the neighborhood of $96.3 million—according to The Los Angeles Times, more than U2, or the Spice Girls, or Celine Dion.

There’s even that requisite bump in the road: Sittin’ on Top of the World, Rimes’ fourth album in less than two years, isn’t entirely living up to its title. Despite a promising debut at No. 4 on Billboard‘s pop charts, the record, now in its 10th week of release, sits at an inauspicious No. 35. Rimes is probably the first artist in a generation who can make a plausible bid for the crossover territory once staked out by Barbra Streisand and Judy Garland. (“If they were going to remake The Wizard of Oz right now,” gushes one TV exec, “it would star LeAnn.”) But the yellow-brick road is fraught with perils both professional (carping critics, the threat of overexposure) and emotional (the recent divorce of her parents). Rimes runs the risk of falling into the Doomed Kid Sensation role held by Tanya Tucker and Macaulay Culkin. “She hasn’t hit that rebellious stage yet,” muses former firecracker Tucker, who enjoyed a run as Nashville’s Lolita in the early ’70s. “But she will. I just hope that the love will be strong enough to get her through those times.”