my blrw should be fuller?

As long as they don't feel thin. They look healthy. They look like mine. Mine are 20 weeks and weigh 4 pounds, I thought they should be fatter too, but I guess they are right on schedule.

BTW they are beautiful!

 

Wyandottes take a long time to fill out. Look at your hens again at around 6 or 8 months.

 

you can do with a better rooster, don't have to be BLRW, a GLW will do the job.