The thing is, you are MEANT to feel hungry. And if you are eating or trying to eat only one meal a day with that level of exercise, then you will be and should be, bloody starving!
Mounjaro should not cause appetite suppression to the point where you do not want to eat. That isn't how it is intended to work, (although it may for a short while after increasing a dose). Unfortunately many idiots and airheads on SM keep banging on about this aspect. That is probably because they have borderline Eating Disorders or are just parroting each other in fear of being Different From The Accepted Norm. Step away from their fuckwittage...
What Mounjaro will do is stop you from overeating and also stop cravings.
What SHOULD happen is:
You will feel hungry at mealtimes and you will want to eat at mealtimes. If you haven't eaten properly recently then you will and should feel, very hungry indeed.
You will eat a proper calorie counted meal and feel full up and SATISFIED afterwards. You will not feel the urge to overeat or to carry on eating after finishing your meal. But look - your meal must be nutritionally and calorifically adequate or you will be fighting your own body and ultimately you will lose and you will binge all your weight back on. Every binge-eater knows that the number one trigger is starving yourself...
This may be what is going on here - if you eat once a day you are simultaneously crash-dieting AND you have to consume more calories than you should need to in a single meal. Why not trust the drug to do its job and work with it and your body? Honestly, even if you got to your goal weight like this, what do you think will happen when you stop taking the drug?
You will not normally feel the urge to snack between meals, and if you do - say because you have exercised a lot - then a small nutritious snack will be perfectly sufficient. If you get a craving for more or for junky stuff, then you will be able to say No. This is not the same as getting hungry at meal times - hunger is not the enemy, cravings are.
As you lose weight you need to recalculate your TDEE and your calorie limit at TDEE minus 500 because it decreases. If you are constantly feeling the desire to eat way below your calorie limit then try to resist because no good can come of it in the long term and you are still in the early stages of a long journey.
You have lost a SPECTACULAR amount of weight in a very, very short time. However if you have starved your body it will be fighting back now, as well as perhaps just needing time to readjust. You say you have PCOS which can make it harder to lose weight as well as bring a higher risk of disordered eating. So please give yourself some credit, and do not worry about a stall unless it lasts longer than 8 weeks. I can't find the link but it is apparently completely normal to stall for a number of weeks when you have lost between 10% -20% of your bodyweight.