Do you have any theories about why drops worked for you, when injections and sublinguals didn't?
And with the sublinguals, I don't think they were as well absorbed as the liquid. Also you have let them dissolve very slowly in your mouth and I didn't always do that. But with liquid, I seem to have much better absorption.
I have to take a LOT of B12 to have any of it useable it seems. I'm sure it has to do with ME/CFS though I don't know the mechanism involved. Back when I was healthy, if I took a B12 supplement, I felt a boost the same day.