Bloods would have been checked for B12 but if within reference range nothing further would be done and it would be accepted you have no deficiency. However if it is low in the range or borderline they SHOULD have done further tests, although unless you present with any symptoms they wont...
I am surprised you are all right on B12 tablets. Pernicious Anaemia (which I also have) means you cannot absorb B12 through your stomach, hence needing to bypass the stomach and have injections into the blood. Amongst other symptoms B12 deficiency can cause neurological symptoms which can...