This explains some:
http://mthfr.net/what-is-mthfr/2011/11/04/

I think you need methyl forms of both folate and B12.
That would be Metafolin (methylfolate) and methylcobalamin.

I cannot find an answer online regarding low binding capacity (transcobalamin) levels. This is a relatively new concept and is a new test in US.

One site I looked at suggested using hydroxocobalamin instead of cyano or methyl, as injections. If you go the injection route, you could try that. The suggestion is to flood the serum and bypass the transcobalamin deficiency... Perhaps the injections often (not once a month) would have an effect.
There is another B12 called adenosylB12... you could try that orally. Take on an empty stomach;
This is one affordable source:
http://www.vitacost.com/nutricology-...Fe8WMgod4U8AUA
Unless your injections are frequent, I think daily oral would be a better route.

Once you get your B12 treated you can do the folic acid as methylfolate. It appears you have some mutation there that hinders methylation. So regular folic acid would not be fruitful for you.(it is not active and requires methylation to work).