Former "Teen Mom" reality-TV star Amber Portwood says she was a substance abuser during her entire run on that MTV show. "This is actually my first time on stage sober, so I'm really nervous," Portwood, 23, tells psychologist-host Dr. Phil McGraw on Friday's edition of "Dr. Phil." "Every time you see me on that show," she added, "I am high." In a clip posted Thursday, Portwood also confirmed that she was sincere in 2011 when she phoned ex-boyfriend Gary Shirley threatening to hang herself.