Nipt Doctor refusal

So I'm 26 years old & this is my first pregnancy. My doctor or Ob nurse never mentioned or offered this test. I brought it up and they told me I'm not at risk and it isn't necessary. I know you can find out gender with this test and they advised me to check with my insurance to see if it's covered first. I called my insurance and they do cover it. When I advised the Ob nurse about this they told me that they will NOT send an order for this test because I don't need it. They had an attitude and told me it didn't matter if my insurance covered it or not they will not let me get this test. Has anyone else gone through something similar? Is it true that only high risk mothers can take this test ? I'm 15 weeks by the way and they told me at my next appointment I would find out the gender but I just don't trust I'll really find out.