Karin posted as I was typing, and she poses another good possibility. Bodyfat testing has an error in measurement, whether you use calipers or the hand-held machines. The time of day, the person doing the measurement, and your hydration will effect those readings.
But still, I believe you are to be applauded for taking steps in a great direction!
Interesting that you have lost so much body fat (congratulations!!!) yet not seen any change in clothing size. I can understand that you might not lose much weight, but if you’ve dropped 9% bodyfat, there might be a little change in the way your clothes fit. Muscle is a lot more dense than fat so if your weigh is unchanged my guess is that your size would drop.
If I were your trainer, I’d be giving you a high five. What does your trainer say?
Were you dehydrated before and now you’re drinking an appropriate amount of water? That could also be part of the reason you haven’t noticed much of a bodily change, but you’d have an increase in your overall health.
frankly, a body fat percentage drop from 31 to 22 % with a stable weight and no loss of inches sounds highly unlikely to me. I am wondering how long you have been training and how far apart those measurements have been taken.
Measuring body fat is not an exact science. There are several methods that can be used but all of them have shortcomings. How well your are hydrated and the time of day can play a role. It is very important to create identical circumstances when measuring.
My best guess is that there has been an error when the body fat was assessed.