i wouldn't worry too much about a 3 lb gain over 10 days, especially if you haven't drastically changed your eating habits and/or activity level. maybe if those 3 lbs are still there a month from now, you can do some re-evaluating, but until then, TRY not to stress (yeah, i know easier said....)
case in point: 3 nights ago, i weighed myself and i was up 5.2 lbs. now i don't usually weigh at night, and i hadn't pooped in a few days, AND i JUST had dinner, AND i had a super extra-salty vodka caesar. then yesterday morning, i was a little over 1lb less than my "normal"...(i pooped! lol, and it was morning, my usual weigh in time). i didn't eat less nor more, i didn't exercise less nor more either.
long story short, our weight will fluctuate (sometimes by alot) day to day. what matters is your average weight over time (and not over 10 days, but over months)
good luck! you are doing great ❤️