I think your plan is the best way to go.  I had a CVS done last week at 12 weeks along and it was the worst decision for us.  The doctor had to keep repeating the procedure because he was unable to get a piece of the placenta.  I finally had to tell him to stop the CVS all together because I was terrified that we were doing more harm than good.  It was a very tense situation.  I was torn up that I had put my baby at risk of a miscarriage.  Since then, I had an ultrasound done and everything seems to be fine from the procedure, they even think that I’m having a boy.  If this is true, I’m going off the dex and will wait and test the baby for CAH when he is born.  I feel like there’s no need to risk miscarriage in order to find out the diagnosis.  I hope this helps!