If it's okay to post this, you might want to try to find a therapist who specializes in CSA.
For me, I needed to see a woman therapist and wanted someone sensitive to CSA. You are not wasting anyone's time and the past does matter. Working through my past trauma issues has helped me deal with my life today. It is hard work, slow at times, but really worth it. Survivors are going to have a hard time trusting and opening up - therapy is not a "race". I am so sorry you had two bad experiences but I would like to say that there are good therapists out there. I wish I knew the best way to find one... I have read that you can sometimes interview therapists over the phone. Flashbacks are hard. I usually hold a stuffed animal, or take a hot bath, or call someone on the phone(even if I don't mention the flashback), or take a walk, or sit on the floor and cry until it passes, or journal about it.