Does this sound familiar? You think you're doing everything right but the scale just isn't moving.
Of course physiologically, plateaus don't exist. If you eat fewer calories than you burn you ought to be losing, and if you're not, perhaps the scale's measuring constipation, water retention or clothing.
So if you're not losing, and it's not just a trick of the scale, either you're burning fewer calories than you think, eating more than you think, or some combination therein.
Certainly as the body loses weight it adapts and metabolism may well slow which means you might be burning less than when you'd started, which means that you might not be plateauing - perhaps you've just reached a new equilibrium, a new floor.
Ultimately though, there are really only two questions you need to ask yourself.
1. Could you eat any less and still enjoy your life?
2. Could you exercise any more and still enjoy your life?
If the answers are "No", there's nothing left for you to do. If the answers are, "Yes", well then by all means tighten things up.
Do remember though, if you can't happily eat any less and you can't happily exercise any more then guess what, you're probably not going to.
Ultimately it doesn't matter if it's a plateau or a floor. The scale doesn't tell you how you're doing, you do. And if you can't happily do any better, you're doing great - scales and plateaus be damned.