If you want ORD, bid the 737 at an east coast base such as LGA or DCA. Based on the last vacancy bid, you'll be to ORD inside a year and the commute won't be awful while you wait it out.
Even if you wind up in an A320 (not likely since they usually go senior to the 73) or the 190, you can still retrain to another airframe after six months. But then you have to go back to DFW for a month, which is why I recommend you bid the 737 to start with.
So, don't sweat it... it'll work out for you, probably in very short order. Welcome to AA!