one step forward and six steps back

I’ve had weekly EMDR sessions for the better part of two years tackling my negative beliefs that were a result of c-PTSD. I’ve had a few breakthroughs where I had incredible clarity for a while, but they never last long. My body is incredibly tired. Even though I can feel my negative beliefs changing and my memories aren’t as paralyzing to me when I intentionally think about them, I’m having flashbacks more and more frequently and have a hard time controlling my emotions. My therapist says this is normal and I should expect to feel this way, but it’s starting to feel like there’s no light at the end of the tunnel. Has anyone else dealt with this kind of burnout/have any advice?