Gilbert,
It's too late to change what's happened with this heifer, but it might be good to look into your pastures before buying your next heifer. A couple of years ago we had a "great" heifer we couldn't get bred - tried everything (even wrote Cowboy - who offered some great advice). Finally the vet asked if he could flush her to look at her eggs and see if that gave a clue. Flushed her and got 22 No 1 eggs - looked at 3 under the scope and they were perfect. Let the heifer cycle again and rebred, still couldn't get her to take. Finally we thought about environmental effects - pasture, feed, water, etc.. Send a forage sample off and guess what - we had a fungus infested fescue pasture. The result of the fungus is that cattle kept a constantly elevated body temperature -2-3 degrees above normal. Not enough for her to appear or act sick, but the elevated temperature adversely affected her ability to maintain a pregnancy. Changed her pasture and waited 60 days, rebred her and guess what - she stuck. Calved normally and rebred on time the next year. My point is that not all breeding problems are genetic. I don't keep problem animals, BUT I try to be sure before I sell one that the problem is the animal and not the manager.
Just a thought to keep in mind.