All a scale does is show weight change up or down.
It does not tell you WHAT it is from -- pee, poo, drank a lot of water, just ate dinner, put rocks on your pockets, etc.
It's normal to flux up to 3 lbs in a day as your body processes all the things it needs to do with digestion.
So I'd suggest learning your own personal range and relax a bit.
Think about not pressuring yourself so. You can totally be in a bathing suit whenever you want! They make them in all sizes!
Before you carry on with the physical side of dieting you may want to think about spending some time on the emotional side.
Because 1/2 lb? Could have just been a poo! Then to derail into a binge over it for several days? Then heap doom and gloom over your upcoming vacation to the Cayman islands?
I'd be all ...
"I GET TO GO TO THE CAYMAN ISLANDS!
"
rather than
"I am terrible! I had a 1/2 lb show on the scale!"
What you focus on, you get more of, and then the good stuff passes you by unnoticed.
Don't live life that way. Losing weight is a journey and it takes some time. Having a good attitude on the journey is so much more calm than chronic body bashing... and it helps make the journey bearable.
Hang in there!
A.