It seems like it's a mix of your anxiety and just that you're not eating very much. My weight can fluxuate by up to 5 pounds from day to day based on where I am in my cycle, how much I ate the night before, if I'm regular or constipated, etc... So, 8 pounds i 4 months would not worry me at all. For those trying to lose weight about a pound a week is considered healthy. You've only lost half that much.