Why would you say she's an EE and not an Ameracauna?
Because she is not a "standard" color. By the Ameraucana Breeders Association's own rules - anything that is not "Standard Colors" are called Easter Eggers. Your bird is not White, Black, Blue, Buff, Wheaten, Blue-Wheaten Silver or Brown-Red. Therefore - your bird is an Easter Egger. She may also have green legs, which means yellow skin. No Ameraucanas have yellow skin. Come over to the EE's thread where we all love our birds for the differences in them. https://www.backyardchickens.com/t/273489/the-ee-braggers-thread