These are listed as the 12 Olympians:
Zeus
Poseidon
Hades
Hestia
Hera
Ares
Athena
Apollo
Aphrodite
Hermes
Artemis
Hephaestus
So, it appears that Demeter and Dionysus are not part of the big twelve and you left out Hestia, who is.
Note: People! Hades, Poseidon, and Zeus were brothers. He was certainly one of the big twelve whether or not he chose to associate with them.