Low b12 symptoms but a high level in blood

Blood level after 2 days of supplementing was 1111, but I definitely have/had the b12 neurological deficiency symptoms (double vision, loss of colour saturation, neuropathy, freezing cold etc) which appear to be SUBSTANTIALLY improving after supplementing 10,00mcg sublingual daily over the last 3 weeks. I believe my vegetarian/vegan (recently pescatarian) diet was to blame even though I was using a b12 sublingual liquid (but not taking it properly).

My question is this: is 10,000mcg daily too much? I still have some symptoms that are coming and going.

If it’s too much, any advice on what I should be doing is greatly appreciated 🙏