if he is growing that fast i would not give him any more,stick to the diet hes on.seems he is pretty normal.as for the other 2 possibly they have parasites restricting there growth.it wouldnt hurt to get some panacur from your local vet and treat the 2 smaller ones.how much do they weigh?
They dont have parasites. They are normal sized as they are the same size as other snakes their age.