Have you measured it in the blood? Even if your B6 is fine, what about B12? That has even worse bioavailability from plants or supplements. Again, you need to measure it, furthermore B12 takes years to deplete.
The problem with B12 is more with low cobalt in the soil and genetically low absorption. There are now even bioactive plant forms of B12 like water lentil.
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.