First of all...YOU ARE NOT POWERLESS!!! Cancel, cancel that thought! You may not be exercising your power...but it is in you as it is in every one of us! You are not an exception to this!
Now that that is out of the way...I would not recommend fasting for anyone who has an eating disorder...even bulimia. Eating disorders involve extremes of eating patterns...and fasting just contributes to this pattern.
Instead, you should focus on a nutrient-rich sensible cleansing diet that is primarily composed of fresh vegetables and fruits...if you tolerate them well. Include a good quality protein...animal or vegetable...and juice regularly to provide additional cleansing effects and nutrients. Also...drink lots and lots of water.
You will need to relearn how to eat in moderation...and the only way to do that...is to do it!