It may be one more, but if none comes out, dont be afraid. It may be she is somewhat swollen in there. It is a common worry here, people thinks one is left, but 9/10 it was nothing left.
If the mamma is contented and not stressed nor in visible labor, you dont need to worry.
The real danger is to be sure all mothercakes did come out. Easy not to notice them, but if you are sure they did come out, so
Don't cut, tear with your fingers as far away from the kitten as possible. If you tear a cord it seals itself up. Cord sissors in a hospital are blunt - very blunt - for just that reason.