Many people play ultimate not on organized teams but in a venue called "pickup"
Its a park somewhere that everyone randomly agrees to meet at and play at.
Generally people bring light or dark shirts and join whichever team needs folks.
The games can last for hours with a constantly rotating line of players.

Although the warm weather is fading there is still an opportunity for you to keep playing some ultimate in a pickup format like this.
At Welsh Park in Rockville at 10 am on Sundays there is a group meeting.
Some other high schoolers will be there and they are welcoming to beginners.

Especially if you like in MD this could be a great way to keep your game up through the winter.

If you dont live in MD and you want more info on other pickups in the DC area let me know,
Dave