As you know I am also copper deficient with no other cause found and autoimmunity is suspected.
My ferritin is also below the normal range.
I have been supplementing since February with 2-4 mg Copper a day and just had my levels rechecked again. They will go in to the lowest of the normal range, but won't budge from there. My dr. said I could take a higher dose.
I have read about people with malabsorption syndromes and that the metals get pushed into the organs and brains so I do think about that, but that's not to say I wouldn't try a few infusions if someone would let me- especially since I don't think I could have that issue after so many years of being healthy.

Also *It's been over a year since I've had gluten, so I don't believe it is celiac.
If I had doctors willing to do the infusion or the IVIG, I'd go for the copper first and IVIG last.