There can be all sorts of genetic errors we are learning since the genome project ended.

Did you ever have a homocysteine test or MMA test? These are specific to B12 utilization and not just a serum level. If MMA is low and homocysteine low, then you are using both adequately.
If your MMA were high...that would indicate something is wrong with perhaps your methylation chemistry, which activates cobalamin to its methyl form which is active in the body. If this cobalamin could not be utilized it would build up some. High homocysteine also suggests failure of methylation chemistry.

Also in the B6 area, B6 (pyridoxine) is not active either and has to be phosphorylated by pyridoxal kinase to P5P in order to work in the various enzyme systems in the body. Methylcobalamin, methylfolate, and P5P are the 3 cofactors to change homocysteine to SAM which then carries the methyl group around to many many systems.

The autism community is pretty active with nutrient treatments and research. There is one study done on autistic children, before vitamins were given (hoping to improve their functioning) that found very high B6 levels in these children.

This is my B6 thread:
http://neurotalk.psychcentral.com/thread30724.html

Lots of information collected there to explain things.

Keep in mind that getting tested when you USE a supplement changes the range meanings considerably. The ranges were done on people who did NOT take anything extra. So they only reflect non-supplemented tests.

The autism study is in post #4.

This is not to say you are "autistic", but that group surprisingly
tested high in the face of no vitamin intakes. There may be other people with unique chemistry who would test oddly too.

Many foods are fortified now, too, which would provide vitamins you may not think of.

Low B5 is unusual... there is a carrier for this vitamin, which shares Biotin and lipoic acid... so B5 might get bumped off depending on the other two's activity etc. B5 is not commonly low in most people. It is very common in food.
Here is a good monograph on B5:
http://lpi.oregonstate.edu/infocenter/vitamins/pa/

Notice low levels cause burning painful feet.

If you are interested or want to find out more, you could get INTRAcellular tests done that show the vitamin levels inside cells, instead of serum type which you probably had.
Spectracell labs is one company who do this testing.