Oh well, another member of the club here. Diagnosed with Pernicious Anaemia a couple of years ago also, and getting my 4 shots of B12 per year too, At the beginning even several per month, can't remember the exact numbers. It has effects on the brain/memory, isn't it so? 
Always tired and sluggish, but the blood tests say that most values are in the green range,
The doc promised me that I should reach 80 years; I was 78 last month…
nonetheless hope to prove him wrong!
Regards,
Hans