Vitamin B12 supplements require very high doses due to poor bio-availability. You have to ask yourself, could this be a healthy diet when you effectively need a pharmacy to maintain it? What else is your body missing out on that we might not be aware of?

That's why I say a plant-based diet is science experiment with no plausible basis in evolutionary history. I'm not saying it's bad per se, I'm saying we don't actually know if it's good.

Looks like you have done your homework and are not in fact deficient, at least in terms of those biomarkers and reference values. A lot of plant-based dieters are not that diligent, affluent or educated.