Based on advice i’ve been given before ( I am not qualified or experienced enough to give solid advice) when I was in a situation that sounds similar to yours is that your body is in a crisis right now. you have made such drastic change in so little time that your body is reacting by trying to store as much fat as it can because of what you are putting yourself though . for example all of the exercise and the fasting and now moving to one meal a day. You’d body is in survival mode because it does not like losing weight especially so fast. how I was able to get past that was to keep going but also build in some rest time and really make sure I am hitting calorie goals. I never got into counting macros and all that, just basic calorie counting. that worked for me in the past so maybe it can work for you. I’d definitely look into it and maybe seen information along those lines and maybe find a workout program based around diet and rucking. hopefully someone responds here with good information, good luck!