Here is another shot with her cage mates.
Where can I find any pictures of Silver Leghorns to compare.
I have googled with little success. She is 15-16 weeks.
She does have some similairities to the picture of the Americauna from the link posted above.
I am not an expert on Leghorns by any means, but your girl does have a general Leghorn look about her. I really can't see the comb in the photo, is it single or other--a closeup would really help. The Silver Leghorn does come in a Rose Combed variety as well as a Single Combed variety http://www.amerpoultryassn.com/APA_Recognized_Breeds_6_2010.pdf ).
Sorry can't help with the photos. You could try doing a search for Silver Duckwing Leghorn and see if it gets better results.
Is there a reason you are doubting the breed since you were told it was a leghorn when you got her?