Should you throw away your scale?
I don't see anything wrong with weighting yourself even everyday (if you really want to), as long as you learn how to interpret the reading.
Stepping on scale regularly provides quick and continous feedback. It's relatively easy to miss the weight piling up while wearing loose and stretchy clothes.
Keeping an eye on that number, can give you a good reality check, which can help you stop the weight gain in its tracks before it gets out of control.
However, a few pounds more on certain days doesn't mean you got fatter while sleeping. Daily weight fluctuations are normal and to be expected, especially when you're a female.
My weight can fluctuate up to 6 pounds from day to day.
It depends on my menstrual cycle, bowel movement, how much and what I ate the day before, whether I worked out or not, how much I drunk, how much salt I used etc.
So instead of freaking out because of one reading, focus on a weekly or monthly average.
With saying all that, keep in mind that body weight is just ONE OF the ways of tracking your progress. It's best to use it along with pictures, body measurements, and the way your clothes fit.
If you're strength training, take into account the fact that muscle tissue is more dense than the fat. So it is possible to drop a dress size, while actually gaining a few pounds.
Here's a picture that ilustrates it very well (this is not my client).