Actress/Singer Rihanna attends the Los Angeles premiere of "Battleship" at Nokia Theatre L.A. Live on May 10, 2012 in Los Angeles, California. Credit: Kevork Djansezian/WireImage.com 
 
 Rihanna is running herself ragged. 
 
 The unattached, "Where Have You Been" singer, 24, is at work on her seventh CD -- and trying to squeeze in some more zzz's! Recently, she opened up to Us Weekly about her jam-packed calendar -- and the effect it's having on that famous beach bod. 
 
 PHOTOS: Rihanna's sexy bikini bod 
 
 Recently, the pop diva made the leap from the recording studio to the big screen with her star turn in Battleship. "I want to do two more [movies] before touring again next year," Rihanna gushed to Us of her filming experience, even though, "My schedule is crazy!" 
 
 So crazy, in fact, that the Barbados-born beauty was hospitalized for fatigue following her appearance at the Met Ball last month, where she stunned in a black, reptile-inspired Tom Ford gown. 
 
 "I got no sleep [beforehand]," Rihanna explained. "It's harsh on your body!" 
 
 PHOTOS: Rihanna, then and now! 
 
 Her hospitalization -- and her shrinking bod -- have some fans fretting that she's dealing with something more serious, though Rihanna assures Us her nonstop schedule is the only thing to blame. 
 
 "I'm a size 0 -- and not happy about it!" she says. "I went way too far. I prefer myself a bit chunkier. I want my old butt back!" ||||| Rihanna was spotted in Miami with Knicks player J.R. Smith, who had a recent run-in with the law. 
 
 Rihanna definitely has a type. 
 
 Sources tell us that the “We Found Love” singer has found another tattooed bad boy to stoke her considerable passion: New York Knick J.R. Smith . 
 
 We hear the danger-loving Barbadian beauty and the ballplayer have been quietly keeping time together for weeks, and one down-South source tells us that they were “definitely hanging out” in Miami this weekend after Smith’s run-in with cops there on Thursday. 
 
 Smith, 26, was picked up in South Beach on an outstanding bench warrant for driving without a valid license. He reportedly bonded out on Friday, in plenty of time to hang with the pulchritudinous pop star over the Memorial Day weekend, and that coincided with the culmination of Urban Beach Week, which the Miami Herald called “South Beach’s biggest party of the year.” 
 
 Our source says Rihanna, 24, partied at LIV nightclub in Miami’s Fontainebleau Hotel Sunday night and was joined there by Smith. 
 
 Rihanna’s former flame Drake was also in the building and was photographed with the sexy stunner, who is once again sporting raven tresses after posting semi-nude photos of herself as a blond on the Internet. 
 
 Just like Ri-Ri’s ex, Chris Brown , who assaulted the singer three years ago, Smith has had some serious run-ins with the law and is one of the most heavily tattooed players in the NBA. 
 
 Smith drew the ire of NBA executives earlier this year when he posted a picture of the naked derriere of a woman in his hotel room on his Twitter account. The league fined him $25,000 for the transgression. 
 
 The NBA player was also sentenced to 30 days in jail in his native New Jersey for reckless driving following the June 2007 car accident that killed his good friend Andre Bell. 
 
 Smith admitted that he ran a stop sign with his SUV and the ensuing collision with another car led to both men being ejected from the car. 
 
 Bell died two days later from head injuries, while Smith eventually served just 24 days stemming from the five traffic tickets he was issued for the crash. 
 
 Earlier this month, Rihanna reportedly was spotted sitting on Smith’s lap and flirting with the basketballer at Veranda nightclub in the West Village. 
 
 This isn’t the first time the “Umbrella” ululator has hooked up with a professional athlete. Rihanna previously dated Los Angeles Dodgers superstar Matt Kemp , who, by the way, also sports quite a bit of body ink. 
 
 The two broke up in 2010 after almost a year together. The singer has also been linked to Shia LaBeouf and Ashton Kutcher , among other Hollywood heartthrobs, although those relationships were never confirmed by either Rihanna or the actors. 
 
 Rihanna’s spokeswoman could not be reached for comment by deadline. 
 
 Contact Gatecrasher: 
 
 Frank DiGiacomo: fdigiacomo@nydailynews.com 
 
 Carson Griffith: cgriffith@nydailynews.com 
 
 Adam Caparell: acaparell@nydailynews.com 
 
 Follow us on Twitter: @NYDNGatecrasher
– Rihanna's derriere isn't as ample as it once was, and the singer doesn't like that fact. "I'm a size 0—and not happy about it!" she tells Us Weekly. "I went way too far. I prefer myself a bit chunkier. I want my old butt back!" The 24-year-old lays the blame on her crazy schedule, which apparently has her losing out on sleep ... and landed her in the hospital post-Met Ball. "It's harsh on your body!" she says of her jam-packed life. And her run-yourself-ragged approach has many worried she's falling apart. Chris Brown and Drake apparently don't mind the size of Rihanna's booty; click for the latest on their reported bar brawl over the singer.