No matter what "she" is, that is one beautiful chicken. I have Ameraucana's and my biggest issue is with the shape of the comb of your pretty bird. If you have a girl, I think it is an EE, not a true Ameraucana. The comb does not look really large or overly red though(I had an RIR Roo with that type of comb, it developed much earlier and was bright red by the time he was 6 weeks old) It is tough to sex Ameraucanas, My birds were 12-14 weeks before I could tell that I got 4 Roos and 2 pullets. Good luck and I hope you can keep "her" no matter what "she" turns out to be. I'm thinking pullet for my two cents, lol.
Pretty sure that's a chicken, but do her rear feathers look like they're curving downward? They kinda look that way to me. Totally a novice eye, but I thought I'd chime in b/c after looking at a bunch of the gender forums, I think these are my fav posts. The guessing game!
I am guessing on her age.. she could be older but she is kinda little.. I got her at the end of July and she was probably 4-6+ weeks then SO.. she could be as much as 10-12 weeks. I know that kinda sucks as a time line but since I didn't hatch her I can't give you a date range