miniature poodle first heat cycle

Question
I have a few miniature poodles. 2 of my bitch's had their first heat cycles at 11months old. I have 2 other black mini poodles, who are now 15 1/2 months old. They are litter sisters and i have been checking them every day from 6 months old and both of them have not yet had their 1st heat cycle and dont show any sign of coming in either. Is this normal?

Answer
No this isnt normal.  Usually they will come into heat around 12-13 months at the latest.  There is an easy thing you can check to see if they may have fertility issues.  Have your vet check their thyroid.  If the thyroid is low then they will never be able to get pregnant.  There are drugs that can be given to fix that, HOWEVER, you would be passing that genetic defect on to the next generation if you did breed them.