You need a hematologist who specializes in myeloproliferative disorders. Maybe you can find one in network?

Many of the research hospitals have specialists in this area: Mayo, MD Anderson, Duke, etc.

If you don’t think you’ll be able to seek a second opinion, I would ask your Dr whether you have a CALR mutation that is causing ET, and if so, whether she has considered ordering a bone marrow biopsy to confirm her diagnosis.

You might also ask her if she can specifically refer you to a specialist.

I sought a second opinion because I was asking questions that my Dr did not seem to be able to answer. It clearly was beyond his expertise.