Those last two pictures do look like roos. It was not possible to see those combs and wattles in your other pictures. Their crests and hackles seem quite underdeveloped for their age, are you sure they are 6-7 months old?
6-7 MONTHS old? They do not look at all like silkie roosters - unless they are incredibly slow to develop. All look like pullets to me. Here is a picture of my 6-7 month old rooster, Percy:
Notice Percy's massive wattles and comb, his long streamers and hackle feathers and his large size...