Here are the eight sub species of Double Yellow Headed Amazons (Amazona oratrix) as recoginzed by the Amazona Society (
Amazona society):
Double Yellow Headed Amazon
Amazona oratrix oratrix
Belize Double Yellow Headed Amazon
Amazona oratrix belizensis
Yellow Crowned Amazon
Amazona oratrix guatemalensis
Yellow Naped Amazon
Amazona oratrix guatemalensis
Yellow Crowned Amazon
Amazona oratrix Hondurensis
Yellow Naped Amazon
Amazona oratrix hondurensis
Greater Double Yellow Headed Amazon
Amazona oratrix magna
Tres Marias Amazon
Amazona oratrix tresmariae
Interestingly enough, the Yellow Crown is listed in here and is not known to be one of the more aggressive of the Amazons as far as I know.
I can't say for certain that Amarillo is or isn't a Belize Yellow Head. I can't say that she is the most unagressive bird I have ever met simply because she's a female or because perhaps she is a sub species of type Belize. I have heard from others that their Belize, or what they thought of as the Belize sub species are also very docile. I do not know whether or not they had males or females. I guess it is all up to interpretation.
I do know that I love my girl and that she turns 12 today!