I haven't been in your position but I have had 6 children.
I have never ever had in any of my pregnancies a NT test or a blood test for DS.In fact I had never heard of any of those tests before 2 yrs ago when I joined.
I have one child with a disability (Aspergers) and was considered very high risk as I am also RH neg!
I was told during my last 2 pregnancies I was told that I had to have an Amnio but like you I would definately refuse it.