I absolutely understand your concern about considering changing therapists. I recommend you consider the following, as I do not believe it's black or white as to whether it's necessary to change, depending on your answers:

1. Have you seen improvement?

2. Is your therapist confident that she can continue to serve you, including being willing to do ongoing education herself, if needed, to give you more tools?

3. Do you have a strong therapeutic alliance? I believe a lot of the healing that happens in relationship is in the bond itself, this has been true for me, and there is research to support it.

4. Certain types of therapy have been shown in studies to be most helpful for PTSD: some studies mention CBT or EMDR, for example. Does your therapist provide a type of therapy that is conducive to healing your symptoms? (In my case, I don't find either of those perfect, and we use other methods, so I don't think one size necessarily fits all, because along w/PTSD we're all unique and may have other challenges and strengths with which to work.)

5. What does your therapist believe is best? Her first obligation is to your healing, including referring you to someone who can help you better if she ever believes it would be beneficial or necessary.

Hope that helps!