I'm a recovering binge eater and I can hear your pain. For me, I sought help via: inpatient treatment (dropped out), day program, and outpatient therapy and meds. What was most helpful was the day program. I got to hang out with other women with eating disorders. I was the only overweight one there - the rest of the women were anorexic or bulimic, but I felt accepted.
When you said that you "only" purge once a month, I think you haven't really grasped that you have a serious, life-threatening problem. Check into some sort of program and maybe you'll realize how your eating disorder effects your daily life.
I can't say that I am completely healed, but when I have a binge, I no longer shame myself. I simply throw the food wrappers away and carry on with my life.
I hope you find something that works for you and keep posting