Angel...

Don't weigh yourself at different times of the day and then try to compare those weights, it will just drive you buggy! Body weight can naturally fluctuate as much as 8 pounds from morning to evening due to the foods we eat and the fluids we drink. Food and water do not magically lose their weight just because we put them in our mouths. Try to avoid jumping on the scale several times a day; it's pointless and will only get you frustrated.
The best time to weigh is first thing in the morning after using the bathroom and before eating or drinking anything. If you weigh with clothes on, try to make sure that it's always the same clothes or, better yet, weigh yourself naked.
I won't go so far as to say throw the scale away (your mom might not appreciate that, anyway), but don't rely on it too much as a way to gauge how you're doing. Your measurements and how your clothes fit are a much better way to tell how you're doing.