There is lack of consensus about the definition of B12 deficiency. Some define deficiency as serum Vitamin B12 levels less than 135-203 pg/mL (100–150 ρmol/L) while others use a Vitamin B12 less than 338 pg/mL (250 pmol/L).
Check your levels of HC and Vit B12.
If your HC levels are greater than 6umol/l, you will need Vit B12.
If your Vit B12 levels are in the lower normal range, you will need B12 supplementation so that the value is OPTIMAL. Based on that you may need to take 0.5mg/day B12 or more. You may use either of the two forms. Practitioners recommend the methyl form since it has slightly better absorption.