I found some pics, first pic is 13 weeks second pic is 10 weeks
https://www.amazon.com/photos/shared/OBBZCjpnR2-9UqjE2Iy0gg.3RqxvUtjfaJIsedwoegYGZ
https://www.amazon.com/photos/shared/1pTV9UYuQf6MWkQrO6zhaA.vmH4Vch3Ivo947BEMwr3-C
Yep your ameraucana is a cockerel, I got a splash ameraucana "pullet" last year and it looked identical at that age, by 13 weeks its was a confirmed cockerel.