Backing down when hunger returns is the right instinct rather than pushing through. The 2.5-3.5 range is where most people find stable appetite suppression without the side effect load of higher doses.
100 lbs down with 18-20 to go is close enough to goal that the hunger returning may actually be the body defending the lower set point more aggressively - the final stretch often needs a dose recalibration to get the signal back to where it was in the first 6 months.
Titrating down is the right call compared to cold turkey - the hunger management is much more controllable that way. The house rule on trigger foods is honestly half the battle at that stage. I did something similar - the medication manages the signal but removing the environmental cue removes the feedback loop.
The medication continuing to provide value beyond appetite suppression - metabolic markers, blood sugar stability, inflammation - is why some people keep taking it even when the hunger effect fades. The 'still taking it because' is a reasonable calculation depending on what those other markers look like.