I know how much I love updated pics so I took some yesterday of the black and blue ameraucanas (general consensus was both boys), to see if anyone thought differently now that they are 18 weeks old and have filled out nicely. I have also included a pic of our 12 week old splash ameraucana, thinking boy but always love to see what others think!
The Blue Ameraucana and the Black Ameraucana are definitely pullets - not roos. At 18 weeks, you'd see a much larger comb (even in Ameraucanas) and you'd see stringy hackle and saddle feathers.