My thoughts are with you and your family.
We were in a similar situation about 18 months ago, my husband was really ill and most of what I read about AL Amyloidosis, when we finally got a diagnosis, seemed incredibly negative.
Being able to read, both on here and on social media, about the experiences of others living with this disease, helped us to find some hope. You do now have a diagnosis and are in touch with the right experts it seems. In our case treatment initially felt as though it was making things even worse, but gradually they got much better.
I can't promise you that things will get back to how they once we're but there is hope that they'll get better. Do keep chasing for that NAC appointment.
Take care.