The 14-year-old girl, with blond curls, French-manicured nails and white sneakers, tapped her fingers nervously as she waited yesterday to go on "Daily News Live" on Comcast SportsNet. "I'm not nervous," Natalie Gilbert assured a reporter with an infectious smile. "I'm excited." The Lake Oswego, Ore., teen became famous last April after she forgot the words to "The Star-Spangled Banner" before a Portland Trail Blazers playoff game. In front of about 20,000 people. Gilbert was saved when Blazers coach Maurice Cheeks came over, midsong, to sing the rest of the national anthem with her, encouraging fans and players to belt...