How do you deal with fatigue that accompanies autoimmune disorders?

Did they check your B12 and iron levels? If your B12 is deficient, they should give you a B12 shot. Or you can take a daily sublingual (under the tongue) B12 supplement, which is better absorbed than capsules.

From NHS:
"Vitamin B12 or B9 (commonly called folate) deficiency anaemia occurs when a lack of vitamin B12 or folate causes the body to produce abnormally large red blood cells that cannot function properly.

Red blood cells carry oxygen around the body using a substance called haemoglobin.

Anaemia is the general term for having either fewer red blood cells than normal or having an abnormally low amount of haemoglobin in each red blood cell.

Symptoms of vitamin B12 or folate deficiency
Vitamin B12 and folate perform several important functions in the body, including keeping the nervous system healthy.

A deficiency in either of these vitamins can cause a wide range of problems, including:
extreme tiredness
a lack of energy
https://www.nhs.uk/conditions/vitamin-b12-or-folate-deficiency-anaemia/#:~:text=Contents&text=Vitamin%20B12%20or%20B9%20(commonly,in%20each%20red%20blood%20cell.

CARVEDILOL CHANGED MY BREATHING

Iron is fine but I don’t think they’ve checked B12. Thanks!

My favorite folate source is lentils. One cup of cooked lentils will provide 90 percent of the daily value of folate. There are other sources of folate, like black beans, but they will provide a lower percentage of the DV. I prefer to have the natural form of folate instead of the man-made folic acid that can cause problems.

There are times when I feel fatigued while doing all the "right stuff". like taking my daily dose of sublingual B12, and I realize that it has been awhile since I had lentils. After having lentils (folate/B9), I come out of the fatigue.

It is an on going process to allow the red blood cells to bring oxygen to all parts of our body. If there is insufficient B12/B9, I will go back to the "wipe out" feeling.

Once an autoimmune problem appears, fatigue is close behind. Your mind and your body are no longer as one, they often are in conflict. Fatigue is a normal result of the situation. Learn to listen to your body because pushing it beyond it's limits really is not in your best interest. Work to adjust to your body's needs, learn not to let others push you past your new limits.
Eliminate any treatable medical causes, then read and reread the advice @minnesota10 shared.
Thanks for asking this question, it is an important part of autoimmune problems and often overlooked.

From National Library of Medicine:
"Patients who had myeloproliferative disorders had a high prevalence of vitamin B12 deficiency, despite high serum vitamin B12 levels. Therefore, vitamin B12 status should be evaluated in patients with myeloproliferative disorders."
https://pubmed.ncbi.nlm.nih.gov/25730455/#:~:text=Conclusions:%20Patients%20who%20had%20myeloproliferative,in%20patients%20with%20myeloproliferative%20disorders.

GOOD NIGHT'S SLEEP IS VERY IMPORTANT! The other thing my doctor worked out is a daily nap! Usually right after lunch!
Do get LULLED into thinking you are feeling better and get off your schedule and not rest! You pay for it afterwards. That's how I handle my LATE STAGE LYME after 6 years!
GOD BLESS YOU!
SUNDANCE aka RB

I keep beating myself up about how "lazy" I am, even though I know, in my heart of hearts (and my rational brain), that fatigue is part of ITP (immune thrombocytopenia). I keep a to do list, try to keep it short (so I don't feel overwhelmed), and each day I assign one thing that I feel I need to accomplish - and if I get it done, hooray for me, and if I don't - well, there's always tomorrow. I think a lot of it is being patient and kind to yourself.

I have PMR and GCA. I learned to look at my energy like it's money in the bank. If I spend it all, I have to take time and rest to let it build back up before spending it again. Depending on how much energy I use on a particular day, it could take anywhere from a half day to several days to feel rested again. It helped me to know ahead of time that I would be tired and would need extra rest.

Over time and treatment my energy level has improved. At first I would have 1 good day and then 1 or 2 bad days where I was tired and needed to rest. Eight months into treatment I mostly have good days now.