Aaah, The vagaries of the scale. Mine can weigh more or less depending upon which tile it’s sitting on in my bathroom. My mother’s weighs about a pound more than mine.
Wearing different shoes & clothing can give you a different result too. My doctor made me take off my skirt once because it was leather so heavier & they were concerned I was losing too much.
Track your weight at home. Weigh yourself at the same time, in underwear or naked, at the same time, post or pre bowel movement. As long as you’re consistent. There are some easy to use apps to record your weight. Some fancy scales will send your weight & other body stats to your phone.
As long as your trend is going down you should be fine. Did your nutritionalist say anything about the different weights?