Congratulations on your win!
CH AOSB does not automatically equal CH Ameraucana. CH Ameraucana and Res CH Ameraucana are the top two Ameraucanas overall, in both bantam and large fowl. A judge has to be requested to make that designation and, usually, we only do it for District or National meets.
To give an example, let's say we have the following: in Large fowl, Best of Breed was a black cockerel, and the Reserve of Breed was a blue hen. In bantams, the BB was a silver hen and the RB was a wheaten pullet.
We ask the judge to choose CH Ameraucana and Reserve CH Ameraucana. The judge decides that the best Ameraucana entered that day was the black cockerel from the large fowl class and the Reserve goes to the silver hen.