Well they're not 2 years old yet, and you say you've already allowed them to mate. In my humble opinion, waiting for a couple more years would be beneficial, as unexpected health problems might arise. Have you completed all their health testing?
I would also advise you to wait before breeding them, they are still young and have more maturing to do. @SpotTheCat @TheDawg @Ilovemychicks08 @Somewhere_In_The_Clouds