How would I know if I have the right therapist?

Here's what I'm already picking up on from you: 1) you are motivated to advocate for your needs, 2) you value connecting with your therapist in some form, and 3) you have at least a basic understanding of what you want/need from therapy.  

Finding a therapist that fits can be a difficult task.  Every counselor has their own style and some just tend to mesh well with certain personalities--factors beyond our control.  If you look at it in terms of specialties, many therapists will identify those on their company's websites and/or during an intake.  It is important to know what your therapist is competent in because you are sacrificing so much time, energy, and finances into the process!

Figuring out if your counselor is a match for the issues you present with can be relatively quick to discover (usually this happens during intake when the counselor informs the client about their areas of expertise). On the other hand, it may take a few sessions to learn whether or not you feel a connection with your counselor.  In the research we have on clinical outcomes, it is shown over and over again that the relationship is key--treatment techniques alone play a very small role in client change when the counselor-client bond is lacking.  

I wonder if maybe there is a fear here that your therapist may not understand you or may guide you in the wrong direction.  When I have a client with these fears, it's crucial we process their expectations of and goals for therapy, as well as realistic ways I can help support them in those goals that fit their individual needs.  You may find that some therapists don't meet your needs and that's OK.  It's normal to feel discouraged about therapy not working out, but it's important to continue to search for the best match for you.