Where does the feed store source their chicks? I would think that would be the biggest question. Otherwise, I agree with what @NatJ said. The likelihood is that she's an easter egger, and has more in her genes besides white. I doubt she'll breed completely true, since depending on where the...
Actually with her plumage color, leg color and lack of muffs and beard, there's no way she's an ameraucana. Its possible she'll lay blue eggs, but that's only one of the defining traits of the breed.
there's some small differences, and some big ones... here:
https://www.fresheggsdaily.com/2013/12/ameraucana-vs-araucana-vs-easter-egger.html
AMERAUCANAS
Ameraucanas are a pure breed that has been recognized by the APA (American Poultry Association) since 1984. They were most likely...
Easter Egger...
eta: This is a common problem... Hatcheries, and by extension feed stores, spell the name of the breed with an I in the middle: Americana, rather than the proper spelling: ameraucana. By doing this, they trick people into buying cheaper easter eggers, instead of the more...