The good thing with SW is that you can still do these things and lose weight.
The best thing I can suggest is to be completely on plan for the days you don't have plans. So say your plans are across Friday to Sunday, make sure that every other day is strictly SW friendly.
For example, I'm out for a meal on Friday night for my birthday, and because I know about it in advance, I'm making sure that every other day is strictly SW so I don't have to restrict myself completely on my birthday (there's going to be at least a little cake, so I'm making sure I can enjoy it
I think sometimes we overthink everything and worry too much (I absolutely do!!) but all I can suggest is that you enjoy your plans, and just be aware that you may only have a small loss (or maintain) next WI.
It's not the end of the world if you don't lose anything, you'll know exactly why, and just keep on plan for the following week.
I'm hoping this makes sense and reassures you