I got the black cotton flannel to interline the sleeves from Vogue, then washed and dried it twice
I purchased the black lambswool to interline the body from Bergen tailors supply in New York.
The buttons came from an old coat I made and were originally from ebay.
I had a whole block of weekend free time to devote to my new winter coat:

The finished garment measurement on the tissue for the smallest size I had (a 16) was a bit big (my bust is 42), so I graded the pattern down to a 14 (making it 2 inches smaller). I also shortened it 4 inches.
Isn't it beautiful!!
It fits my husband better than it fits me!
I was so mad at myself for falling for this pattern. I should have known better. I did want a coat with a bit of ease so I could wear it over a light jacket or sweater, but this is ridiculous! The drop shoulder plus any pattern Vogue says is loose-fitting is a really bad combination for me. Maybe a size 10 would have worked, but I am going to just have to forget about this one.
I am so glad I made a muslin and didn't ruin my good fabric.
After my epic fail, I wore my nice cozy slanket while doing my online shopping. Sure is warm. I did find a nice coat pattern on ebay. I hope I'll have better luck next time.