Hmm, this doesn’t sound good. Firstly, losing three stone, fucking WOW, well done you, that’s so good, you should be very proud of yourself.
So, if you’re at a size that you are happy with, and feel that it’s a safe and healthy weight that you can maintain, then frankly him wanting you to lose more is full-on assholery. Firstly, because he should be making you feel great about how well you’ve done, and secondly, because this is a serious health issue and ‘just what he wants’ doesn’t cut it!
But I’m not one to write people off (unless they don’t use commas apparently) without giving them a chance, so he needs what we officially call, ‘A proper talking to’. This is where all d/s stuff needs putting aside and you need to tell him how good you feel about your weight, how you don’t believe you need to lose any more, and that he needs to support you in this (and stop being a dick).
if you’ve set that out clearly and he STILL keeps pushing you to lose more despite you not wanting to then we’re entering serious red flag territory and you start to need think about whether he’s really looking after your interests and you first, or if he’s really just a selfish A-hole who doesn’t deserve slim little you in the first place.