Make sure you’re weighing yourself at the same time under the same circumstances if you want accurate comparisons. You said you weighed yourself after a meal at night vs in the morning. You will generally always weigh less in the morning due to dehydration and other factors. I’d recommend going forward to weigh yourself in the morning after you wiz and before you eat or drink anything. Then use that as a benchmark.
I’m 175-ish at the moment and it’s not uncommon for me to fluctuate a few pounds day to day depending on my workouts and quality/quantity of food.