Absorption is dependent on how much B12 the body already has stored. If you were deficient initially, your body would have absorbed a lot of B12. Now that your body stores have been restored, now the body is only absorbing what it needs for daily use.
Another thought is maybe your B12 has lost potency if you haven't refilled it recently...I'd recommend calling the pharmacy and asking how long it will retain full potency.
And another thought is if you have finally restored methylation, perhaps you should switch to a different form of B12, such as hydroxo-B12 instead of the methyl-B12. I'd discuss this with your LLMD.
I hope this helps - good luck,
Chronic Lyme Disease, Chronic Bartonella (clinical dx only), Gluten & Sulfite Sensitivity, Many Food/Inhalant/Medication/Chemical Allergies & Intolerances, Asthma, Gut issues (dysmotility, non-specific inflammation), UCTD ("Secondary Lupus-Like Syndrome"), Osteoporosis, chronic Lymphopenia, etc.; G-Tube; Currently trying to wean off TPN.
Meds: Pulmicort, IV Ceftazidime, Heparin (to flush PICC line), Claritin, Domperidone, Colloidal Silver (used topically), probiotics, Milk Thistle, homeopathy.