If your B12 is low this is VERY serious. For some reason, a very low value is typically used as the minimum threshold in the US and UK (usually 200 pg/mL). So if yours is low then you are really extremely deficient. In Japan they use 450 as the minimum.
I hope by now you have started treatment as this B12 deficiency can cause permanent neurological damage.
You should also have tests for pernicious anemia, which if positive means you will need to get B12 the rest of your life via injection or oral supplement. Your stomach is no longer able to extract B12 from your food when you have pernicious anemia.
