Right off the bat, 57 pounds gone is huge, and doing that at 70 while managing knee problems that limit how much you can move makes it that much more impressive. Nothing about your route here was the easy way. Staying this deliberate and intentional for two straight years counts for a lot.
On what you asked, going off what I've noticed from folks running this long-term:
1) Stalling out somewhere in that year-and-a-half to two-year window happens to almost everyone. Your system has caught up and adjusted. The part where hunger just disappeared without effort in the beginning fades over time, not gone completely, but noticeably less than before. That's not a sign the drug quit working, just that your body settled into a fresh balance. A lot of people bring up adjusting dose or layering in a second medication when they talk to their prescriber about this. Might be a conversation worth having.
2) About the cravings, given they show up occasionally rather than nonstop but land hard when they do, that reads more like specific triggers than a baseline hunger problem. A handful of things people in your position report finding useful:
* Working protein into each meal, doesn't take much, just needs to be regular
* Not letting hunger build too far unchecked (weirdly, grabbing something small right before a craving typically peaks can head off overeating)
* Some people say the pattern lines up with the weekly dosing cycle, roughest around day five or six when the medication's tapering off
One other point worth raising