Firstly have a very good look at your rooster, as he is 50% of what your breeding with. Unless he is a good example of the breed (you need to know what a good example looks like) replace him.
Your hens need to be as good as the male and if you have 4 but only 1 is any good just use the eggs from her to create your strain.
It may take longer but you may breed better birds that are worth more.
Have a look at my web site Marky there is a fair bit about breeding on there.