To my knowledge...
11 people of 1 faction and 1 of the other faction are needed to queue.
Any other combination will work as well, but you are required 12 people to queue and at least one from an opposing faction.
You saying you had 17 of the same faction queued is great, however, if zero of the opposing faction queued, it will not pop.
With how few people it sounds like the p2p server has, this sounds like it is a very high possibility.