Jessica,
I can remember when I was first diagnosed in November 2008. After doing a lot of research, I told my neuro that I did not want steroids or IVIG. He told me that I was really "tying his hands" in my treatment. Well two months later and I was on both steroids and IVIG. Breathing and swallowing were major issues at that point, so both helped me.
IVIG did wonderful things for me! I hope that it works well for you too. The only thing that I can think of is the infusion rate and amount. They calculate the amount based on your weight. The rate is a "protocol" that is generally followed.
Take care ~ Melanie.