First, are you on medication? St. John's Wort is thought very highly of in Europe for moderate depression, but it isn't really on point for anxiety. 5-HTP plus herbal relaxants and a program of other supplements, exercise, dietary changes, and meditation would be the natural approach. A naturopath would be the expert to see about this, or a psychiatrist who practices integrated medicine. As for B12, it depends on whether you need it or not.