Did you make it clear when booking you were going to be using a carseat? Did you specifically request a bulkhead row?
Also why did you not take the next flight and instead turn up at the airport the next day? Did you agree this arragement with US Airways as an alternative to waiting for the next flight, and get new tickets issued?
My guess is there is more to the story, perhaps arguing with crew when they required you to be re-seated which led to you being removed from the flight, then being told they would put you on the next flight 6 hours later, but instead you chose to leave the airport, then later decided to try the next day.