Genetic tests for SMA and Fragile-X

Hello. I am not necessarily "high risk" for the above conditions, but I am over 35 (so I'm high risk for other things). My OB sent me to a genetic counselor and they gave me information about the SMA and Fragile-X tests so I became interested in getting tested (I have no family history or specific reason to worry that I have these). So then I requested the tests through my OB but my insurance denied me. I'm willing to pay out of pocket but it seems difficult to figure out where to get these tests done and at this point I'm already over 21 weeks. Even if they were to find something unusual in the genetic test, then they would still need to do further testing (i.e. amnio) to find out whether the baby has it...and I don't even know if you can do amnio that late in pregnancy?? Seems like maybe it's too late in the pregnancy to even do any of this so I might as well just forget it. Chances are everything is fine anyway.