I haven't had to deal with the change of address so I can't speak on that one. Both my I-130 and K3 are also in Potomac. USCIS honestly won't tell you anything beyond the "Worst case scenario" which is the inquiry date. They told me it was "ready for adjudication" months ago and that's the furthest I got with them directly. Our representative/congressman was able to confirm that our petition is assigned to a specific agent, however, also could not confirm an anticipated approval date. They did notify the agent about the inquiry from the representative. But that's all we've got.
Yeah looks like the majority of us are in the same boat. You should fill out your visa timeline in your profile! It helps keep Visa Journey as accurate in timing as users allow