Your own questions betray you. You say you like to fast for health benefits, but then proceed to ask how much weight you will lose when you already seem pretty underweight. This reeks of an eating disorder, not health.
All that being said, you really don’t need to dry fast longer than 48 and maybe 72 at most. If you’re trying to heal something. If you’re trying to lose more weight, you should seek help, this is not healthy.