[@DeadBeatWalking]Westeros during the days of the Targaryen Kings had nine traditional Great Houses: Stark, Greyjoy, Tully, Arryn, Lannister, Tyrell, Baratheon, Martell, and the Targaryens themselves. The Riverlands of House Tully wasn't included as a historical 'kingdom' of its own (because it was subject to the Iron Islands at the time of Aegon's Conquest), and neither was the Crownlands, as at the time of the Conquest it was simply a border region between other kingdoms. That is why it's called the Seven Kingdoms even though it usually had nine Great Houses with their associated lands. If we were mimicking ASOIAF's political scene very closely, we'd have eight kingdoms of Great Houses staffed by eight players. Plus you, as OP and the royal house, as our ninth.

By the current way you have the structure of this written, your House, the royal demesne, is considered its own kingdom. That will leave us with five subordinate Great Houses—an odd number—if we decided to call ourselves the "six kingdoms" to avoid being the same as Westeros' traditional Seven Kingdoms.

You should make things utterly clear and decide two things definitively: how many players are there going to be, and is the royal demesne going to count as a kingdom?