t's kind of fun to watch Mariah Carey in action these days. The pop-singing sensation is busier than ever - and with a brand new CD on a new label and two feature films in the can, she's unstoppable.   She's sold more than 150 million records; her face and voice are known around the world, but Carey wanted to give movies a try, because believe it or not, she has a self-esteem problem. "I'm driven, because I don't really think that I'm that famous," she said with a slight chuckle during a recent interview in New York.   "I made the choice to start a movie career because deep down, I'm a real ham. Have you checked out my videos?" All joking aside, Carey hopes that her starring role in Glitter will help her become even more famous, or at the very least show another side to her talents.   In Glitter, Carey plays Billie, a young woman who was abandoned by her addict mother at a very young age. Confused about her mixed heritage and sense of being, she is driven to make it as a singer. The film is set in the club scene during the early '80s and, despite some similarities to the character that she plays and Carey's real life experiences, she is adamant to point out that the film is not autobiographical.   "I don't expect people to know my life experiences but - hello - I did not grow up in a foster home. My character's father is white and the mother is black, but with me it's the opposite. It drives me crazy that once someone says it's autobiographical, it's there forever and everyone just believes this stuff. My mom is not an addict and we are very close. I talk to her about a hundred times a day. The only real similarity that I have with Billie is that we both wanted to grow up and be singers."   Kate Lanier, who spent almost two years following Carey's every move, wrote the movie. For the screenplay, Lanier combined a story she had in mind with her observations of the singer, and with advice from Carey herself. "I just wanted it to seem real," the singer says. "I know I'm only 31, but let's face it, I have lived a pretty full life."   Mariah Carey's life has played out like a fairy tale. When she was just 19, she was taken under the protective wing of Tommy Mottola, the CEO and Chairman of Sony Music. He was immediately blown away by Carey's voice (her eight-octave range didn't hurt either) and gave her a recording contract. Her debut self-titled album was released to great fanfare and went on to win Grammy Awards for best new and best pop female vocalist.   A slew of albums and awards followed, making Carey the best-selling female artist in history. In the midst of her whirlwind career, Carey and Mottola fell in love and married in 1993 at an elaborate ceremony in New York where guests included Bruce Springsteen, Barbra Streisand and Robert DeNiro. The personal union ended after just four years, but bound by a contract, Carey was still putting out albums on the Sony label.   In 1997 she released Butterfly, a very personal retrospective of songs that personified her innermost feelings.  "On the Butterfly album, basically every song was based on the reality of what I was going through at the time (divorce, loneliness). That was a time of me breaking free delicately. With my new album, Glitter (the soundtrack to her new film), this is a time of me busting out without caring."   And bust out she has! Carey recently broke free from Sony Music and has signed a multi-million dollar deal with Virgin Records. "I truly feel like I am free. I have never been happier than I am at this very moment."   What makes her really happy is keeping busy. The girl is a workhorse. She is involved in every aspect of her career down to the last detail. She no longer has people telling her what to do - she calls the shots. That is why when Carey finished shooting Glitter, she almost immediately jumped at the chance to star in a low budget independent feature called Wisegirls opposite Mira Sorvino.   "I don't want to be typecast as a singer. I have been taking acting lessons for close to four years now and I have range," she declares. "You know, there were plenty of people who told me I was making a mistake, that I shouldn't have taken the role in Wisegirls but they were wrong. The character that I play, Rachel, is a tough cookie. She's from Staten Island, with her long nails and she's very 'boom boom, you're not messing with me,'" she says.   Carey has learned a lot from her past experiences and seems to have things under control. " I can't tell you how much acting has helped me look at who I am. I'm living for being that character (Rachel) right now. She is all about self-empowerment. The process of studying acting and learning about myself, and not blocking every feeling, has really helped me grow as a person. I feel like I have gone through this intense personal metamorphosis that helped me stop being a scared, manipulated girl who was told what to do. I was insecure and everyone took advantage of that. I can tell you things are going to be very different from now on."   Mark her words, Carey is a girl with a mission, and given her drive and ambition she's got plenty more to show the world. - Bonnie Laufer-Krebs