1mg is 1000mcg. Pernicious anemia is kind of the real deal:
Vitamin B12 Injection: Side Effects, Uses & Dosage - Drugs.com
Usual Adult Dose for Pernicious Anemia:
Initial dose: 100 mcg intramuscularly or deep subcutaneous once a day for 6 to 7 days
If clinical improvement and reticulocyte response is seen from the above dosing:
-100 mcg every other day for 7 doses, then:
-100 mcg every 3 to 4 days for 2 to 3 weeks, then:
Maintenance dose: 100 to 1000 mcg monthly
I do not know whether you are correct about B-12 not driving HCT. I agree it is not typically referred to as such. As I said, my own anecdote may not apply one bit to you
Testosterone dose 56mg/week. It is the lowest I have been on ever, and only once before did my HCT rise... on 150mg/week. None of my doctors thinks this is the cause. It could be, but unlikely.
And again, my blood chem has been messed up by leukemia. Both my primary hematologist and I came up with the same speculation independently that I did not come back to a normal EPO set point after 2 years of anemia. So I also wonder about B-12 in the mix. I am not saying it IS causation, I am saying it could possibly contribute. I continue to mitigate every factor I can control. You mention sleep apnea. Yep, that too... managed. I have no obstructive apnea. Been there did that with CPAP. It made me worse. Sleep HYPOXIA managed with nighttime O2 does the trick. Averaging 97-98% with no drops below 90%.