I think your diet approach is exactly right.... focusing on reduced portions and eating for the right reason...calorie counting, etc. is too much detail right now. Good call.
That fatigue can be several things. It could be mental. If so, you've already started the habits that will bring back your drive and energy.
It could be adrenal fatigue, natural hormone fluctuation, CNS overload, stress hormones, not enough sun...anything!
The key is to focus on the basics. Clean eating, good sleep, regular but not punishing exercise, walking away from drama, and getting outside and having some fun.
You're on track. Let this be the week you made the changes, started the journey and did the best you could for yourself!
"...strength is built one recovery day at a time..." -OMP