You're weighing water. You're weighing your body's ability or inability to lose water at a given time of day, after having eaten various things the previous 24 hours that affect that... You're weighing what you just ate - or what you just didn't eat... and all along you're never measuring your fitness, or your body fat %, or your BMR or your BMI - all those things would tell you more about your body and how it's doing.....
If it gets to the point you're weighing yourself then again a few hours later, it's getting counterproductive, surely? I gave up weighing because in the end it was a diet killer, for me. When I got to the point I was weighing daily - I knew psychologically that was totally destructive and wrong. So now I just measure. If I go up a dress size - I have to rein myself in for a while. If I can no longer do an exercise DVD I used to find easy - or run as far or fast - or be generally as active - I know I'm unfit! The scales were never my friend. After over a year's solid hard work, I had lost almost the entire 40lb I needed to - and was a UK size 12 (US 8), with a 27" waist - I'm 5 foot 6 - and know what? The scales still said I was 'overweight' because I couldn't lsoe that last couple lbs. But I'd lost 5 dress sizes and could run without stopping for 40 mins (in my mid 40s too). So I realised what a waste of time they were as an indicator of anything. It was depressing to have stuck strictly to 1200 cals a day without deviating once for over a year... and an hour a day 6 days a week hard exercise - and to look in the mirror and see size 12 where I had been a BIG 20 - and yet for the scales to knock my confidence. So I binned them. (And I have a tiny frame, my wrists are so small I can still wear my christening bracelet - so it's not like I should be at the top end of the 'normal' range. Truth is, even in my 20s when I made Kate Moss look fat, I weighed a lot more than I looked to weigh. Some people do. Scales tell you nothing!)
I think this is highly counterproductive for you, if you're reduced to weighing yourself over and over in one day. Once a week still doesn't iron out fluctuations due to water retention/your cycle etc. Time to walk away from the scales as that sounds like a well unhealthy relationship you have with them.