I take super B Complex, B levels consistently low

I had multiple intestinal surgeries for adhesions due to complications from Gastro bypass. I tack injections b12 weekly , vit d 50,000 and iron infusion annually (fereheme) my illiocecal valve , appendix and gallbladder all removed. The illiocecal valve and surrounding small and large intestine that absorbs those vitamins have been removed