I wonder about that, too. Whether doing and wanting are ultimately all that different. I'm afraid that I don't have an answer for you, but I do hope your T will see that you are struggeling with that the new lifestyle is one of forcing yourself to adher to new rules, instead of adhering to them because you have inherently changed. I also don't really know if he should have prepared you for it, but I feel at least now, he ought to help you cope with the situation as it is presenting itself.

I do think you can give yourself some grace regarding your weight. Having children affects everyone differently and going through the additional strain of not being able to default to your usual behaviour takes courage and strength. It's okay to not controll all aspects of life for a while and perhaps once you have weaned your baby, you can relax your strict rules a bit and watch your food instead.