That's exactly like my Easter egger roo. I always thought (he) was a hen because he never crowed and was really calm and didn't develop any "rooster feathers". I was told they were all pullets too. One morning I heard a crow and sure enough, I had a rooster. He didn't crow until about 7 months. At the same time his tail started turning green and got the rest of his plumage in.
Some are just late bloomers I guess!
Some are just late bloomers I guess!