your issue is that everyones waste water has different metabolite backups from the initial dosing, and, everyones test kits range.
You are cycled, but not by testing wastewater.
if you changed 100% of the water out, refilled, and retested, it w oxidize ammonia. the other two don't matter. if you cant change it all, you can wait till levels drop naturally which is the varying part. You don't have to assist further, its a wait game if you cant change out your water for a fresh test. the time it takes to register zeroes on waste water is independent of the actual cycling completion date, that date is determined by when a tank can endure a whole water change and still pass the ammonia test. 3.5 weeks is plenty for that= a neat way to see cycling and cycling varations, although cycling itself doesn't vary much at all. all aquariums cycle (meeting this final test) at about the same time frame depending on how the boosters were used.