I love, love, love
Catherine Amelia. One of my favorite combos.
Catherine Fiona is lovely too!
Cate/Kate is my favorite nickname for
Catherine. I also love
Kitty, and
Kit.
Oh, and as someone who goes by her middle name, I can say that in my experience it's a bit confusing with teachers, official documents, etc. If you don't plan on calling her
Catherine, I'd put it in the middle spot if I were you :)