SHE hasn't had more than four hours of uninterrupted sleep in months and, with two children under the age of two, Naomi Watts admits her life is hectic. But she is starting work on a new movie this week and hopes there might be one, or even two more, this year. And, just six weeks after the birth of her second son, she's also thinking about more children. "I love babies,'' says the 40-year-old, who has boys Sasha, 18 months, and