Antibody levels have little to nothing to do with symptoms or need for medical therapy. One can have sky high levels and be completely "normal" and others can barely have a positive test and be on a vent.

I hope your doctor doesn't do anything rash based on a blood test. The fact that you are feeling good in itself would be reason to try cutting back. Three days of IVIG every month is a lot. Most just do 1 day every 2-3 weeks as maintenance. I'm glad you asked about it.