If I don't exercise then I'm literally an exhausted lump on the ground. It gives me energy, but I always start my routine with fast walking to warm up. I have to do it in the morning because then it gives me a ton of energy for the rest of the day. Could you start by taking a fast walk every morning?
Sleeping enough but also on a schedule is also important. 8 hours of sleep if you're doing 11-7 will make you feel much more energetic than if you do 8 hours of sleep from 3-11.
I take a multivitamin but do half dose in the morning with a half tab of calcium and half dose in the evening of both again. My multivitamin is specifically for women and energy/metabolism support.
Eating breakfast helps. I eat the majority of my calories earlier in the day and find I don't really need much later. I also get in around 40g protein and have whole grain carbs and whole fruits and veggies. The food you eat does matter, not in the sense of losing weight (you could lose weight on 600kcal of donuts or 600kcal of lettuce) but in how you feel.
I can't do caffeine either, I'll legit go into the worst anxiety mode ever.
Hydration! Especially when it's hot. I don't really get thirsty so I just drink constantly anyways, otherwise I'll go too long and feel ill.
Stress and emotional weight make you feel extra tired. Maybe it's time for some days "out"/having some light laughs with friends. I get so serious in my E.D. that sometimes it's like I've been holding my breath all week because I've been so focused that I forget to breath so when I finally do it's such a relief.
I also do a quick gentle yoga routine twice a day and I think that helps with all of that.
I don't know if any of that is helpful, you probably already know most of this if not all. I just know that I get very frustrated when I'm tired, so I've worked hard to figure out how to combat it for myself.
But as my old therapist would say, "You can be malnourished at any weight."
And malnourishment can lead to fatigue.