St. Louis Post January 19, 1990, FRIDAY, THREE STAR Edition O'CONNOR IS CONTENT, SHOWING IT SINEAD O'CONNOR says that the title of her forthcoming album, ''I Do Not Want What I Haven't Got,'' aptly reflects the way she's feeling these days. ''It implies that I'm quite content now,'' she says. ''That's sort of the difference between this and the first album. A lot of 'The Lion and the Cobra' was written when I was an adolescent, and naturally adolescents aren't very content, and now I'm reasonably content.'' One source of contentment has been her 2-year-old son, Jake, and her recent marriage to drummer John Reynolds. ''That's certainly helped me to feel happy,'' she says of married life. ''I should have done this years ago.'' ''I Do Not Want,'' due in March, features 10 new tracks, including the single ''Nothing Compares to You,'' ''Three Babies'' and ''I Am Stretched on Your Grave.'' O'Connor says that making this album was much easier than recording her debut. ''And I've enjoyed it more,'' she says.