Are you measuring exactly the same way each time? Note that you’ll get different measurements sitting, laying down, and standing - and for standing, the angle of your pelvic bone can be a factor.
Are you *sure* you’re measuring exactly the same way each time?
It would be a good idea to review the measurement guide on the main forum screen. Even if you’ve read it before, it’s worth going over again.
Follow the instructions step by step, and measure every day for at least a week. If your figures are the same each time, you know you’re doing it right. Then measure at least once every two weeks after that. You can log the results and see if you’re making progress or hitting a plateau.
Remember, “without data, you’re just guessing.”