Listen to everyone here who are only trying to help you and point you in the right direction. Thank you for letting us know that you had an eating disorder.
You really want to seek professional help now, because you sound obsessive about weight loss and that is not what fasting is about. Passing out at work is a sign that you need to stop fasting totally till you figure out why are you in this state. Being on plant based diet will help, but you really need to talk to a professional. We all have our own issues. You are going to get out of this, but only you can help yourself.
Take care of the beautiful body that is given to you.