Don't worry about being bad at EMDR. You can't be bad, only your T can be bad at helping you process through it. They need to be specially trained especially for dissociation. My T asks me questions like 3 things I see, feel, hear, we do knee tapping, breathing, sometimes I will hold a cold Coke can out of his refrigerator. Different things like that until I am back in the room and present. I also work on mindfulness and grounding outside of session. We also have safe places that I go to mentally and sometimes he will put the buzzers on really slow while he has me think of safe places. That is another way to bring me back to the present.