Well, you are in the right time frame for the bloods and NT scan (11-14th week) ... if you were to have those and the results show you to be low risk, then I wouldn't go for the invasive testing (my personal opinion). Then again, I don't know how much more difficult this testing is for twins ... so I guess, I would just ask your physician.
Poor little mite - surely if there had been prenatal scanning done, they would have seen some of the issues (like the ear, the cleft palate and other physical anomalies)...
But these don't sound like genetic / chromosomal anomalies, but physical ones and those should be visible on the anatomy scan.
And you are right ... handling a situation like that takes a lot of patience, nerve, time, money ... and it is very humane to realise, that it is difficult to cope and to question, whether one could cope! And it is a very personal decision, which no-one has the right to criticise (so I hope you didn't feel you were being criticised)...
DH has said to me that he would not want a disabled child ... I think it has to depend to a large degree on the type and severity of the disability. I grew up knowing and loving one aunt with down's and another with arm anomalies (whom I adore, that aunt). The one with the arms was born during the 2nd world war while the hospital was being bombed. The OB was desperate to get back to his family and practically yanked her out, tearing some nerves in her shoulders. As a result, she can't lift her arms very high. But that is not her only issue. Because the umbilical cord was tangled around her arms, they couldn't develop properly, so she can't use her arms / hands like we can. Certainly, her childhood and a lot of her life has not been easy, but she is a fantastic person, with a great personality and an amazing strength of will!
These are things, that I think as a parent can be tough, but are doable and the child doesn't have to suffer... there are of course disabilities that are much more severe and I would laud any parent who can and does cope with those!