If you are seeing the specialist before all of the diagnostic tests have been done, know that a lot of the visit will be focused on you, your symptoms, and also your goals. The doctor will be working to understand when your symptoms started, how they have changed over time and over what period of time, and also will try to judge how severe they are.
They will also provide you with a diagnostic plan, which means usually getting a lot of tests if you have not already had them recently, to help them make a complete and accurate diagnosis.
Make sure you bring with you a list of questions that you want to have answered so that you feel you get the information you need by the end of the visit.