I'll call her a DSH Torbie. I think I see some orange on her forehead? She also looks gray, not black, so....
DSH domestic short hair, a catch-all designation for most cats, includes DMH (medium hair) and DLH (long).
Tortoiseshell (black/orange-based calico with blended hairs instead of seperate patches) BUT...
Blue/Cream in color, so your Nia has a dilute gene that works on her black/orange and turns it blue(gray) and cream(buff or pale orange).
Tabby, because she has agouti, which causes the tabby pattern stripes to appear.
Mackerel, because that is her tabby stripe pattern. Patterns are: Classic, Mackerel, Spotted Mackerel and Abyssinian.
Officially, Nia is a: DSH Blue/Cream Mackerel Torbie! ..."Torbie" is a blending of tortoiseshell and tabby.