It might be a regional use, but I wouldn't say "faltamos una blusa"; for me, the verb faltar is not transitive.
Ayer faltamos a la escuela.
We skipped school yesterday. -> We are the ones who didn't go, not the school.
Nos falta la escuela.
The school is a pending business. -> We need to do some activity in school.
Nos hace falta la escuela.
We are missing school. -> We experience a certain nostalgia for going to school or we aren't educated enough, so we need more of it.