Like you, my weight fluctuates A LOT.

Examples:
A few weeks ago I was feeling good and had lost some weight, but was craving some pizza after work on Friday. I caved and ate the pizza, which was the only deviation from my diet that day. The next day, I weighed in 7 lbs heavier than the day before. The day after that I was 5 lbs down.

Just yesterday, I weighed in the morning like always. Since I do intermittent fasting, I ate nothing over the course of the morning. I then had a health screening with our HR department before lunch. I was 4lbs heavier. Granted some of that was clothing, but I was in scrubs, so not 4 lbs worth.

So l sympathize! Being down 3lbs seems like nothing, since that can be added or gained in a day based on what I've eaten, water weight, etc.

Because of that, I have found weekly averages of my weight to be the best measure of my progress. So I weigh myself every day and put it into a spreadsheet that calculates an average for every week. It smooths out all those fluctuations.

Even then, I really only compare the averages every other week since I have found weight loss isn't linear and a two week window is a better measure of my true progress. So if I'm expecting to lose 1-2 lbs a week, I would expect to see a 2-4 lb decrease every 2 weeks in my weekly averages. Often that will be 0.5 lbs lost one week and 2.5 lbs lost the second week.

Find something sustainable for you. After a lifetime of dieting, intermittent fasting with a high protein percentage is working well for me right now. It's the first time I've experienced steady slow weight loss rather than drastic drops followed by the inevitable rebound weight gain.

Hang in there!