Someone talk me through getting cigarette smoke out of a house?

The half you're probably missing is the walls and ceiling. Smoke leaves a sticky yellow film on every hard surface and that's what keeps smelling after you've washed the fabrics. Sugar soap or a degreaser, a bucket and a lot of rag changes, ceiling included. If you're repainting after, a stain-blocking primer first (shellac or oil-based). Normal emulsion over nicotine just lets the stain and the smell bleed back through.