A low TSH like that if you are not taking thyroid hormone already, indicates potential hyperthyroid conditions like Graves.

Your BUN may be a bit high if you were a little dehydrated. Most people giving blood do it on a fast, and may be a bit dehydrated.

If you were taking your B12 daily at the time of the testing and did not stop it, it would register a false high.
If you were NOT taking B12 and you registered that high here are possibilities:
1) you have the MTHFR mutation and are not methylating cobalamin and it is building up in the serum as the inactive form.
2) you have some form of kidney disease. Some people with kidney problems conserve B12, but not all. If you were not dehydrated when this test was done, the elevated BUN should be rerun soon.
3) you have a smoldering cancer of the liver or blood (leukemia etc).
4) some severe GI dysbiosis (too many colon bacteria), may lead to high B12 levels.

If you were taking a B12 supplement, then it would show in the blood and your test is not very useful, therefore.

I certainly don't understand your diluting the B12 in water that way. That is not necessary, because oral is not majorly absorbed.

If you have that high B12 level and you were NOT taking B12 at the time, then you probably don't need to supplement it all unless you have the MTHFR mutation.