It’s a very big jump from your regular fast and one 48 to 7 days fast. If you want to stretch your fasting window, do it gradually or better yet focus on repeating 48’s. Another thing you could do is check and clean what you eat. TDEE with deficit maximum 500, macros and jurnaling. Combining IF with CICO even for a short period of time.
While you can force quick changes on a scale is that real loss or reconfiguring and water weight changes? I can make myself show an 8 pound loss just by dehydrating myself for example. While there are reasons to do longer fasts by pushing harder you could create other issues. Real weight loss takes time and long term consistent changes. Your goal is to create sustainable loss that can be maintained over a long period of time. You are already seeing change so why not just continue what you are doing to see what happens.