my dr says you can't have Braxton hicks till 23 weeks

So I have been having a lot of what I thought was Braxton hicks contractions. My stomach tightens along with cramping and then subsides. This is my third so I know what it feels like. I am 18 weeks when I brought it up to the dr she said it was impossible before 23 weeks and that's it's probably just ligaments. I have that too so I know the difference. It's frustrating to me that they won't even humor the idea that maybe I really am having them a lot and maybe they should check on it ya know? What would you do?