Sounds like you are having a really difficult time! There are no really good medications that can completely chill out someone with PTSD. With therapy and medication, things can get a heck of a lot better though.
As far how to talk your doctor, try making a list of what you are experiencing, and any questions you have. Then bring the list with you to the appointment, and share it with your doctor by reading your list or handing it to your doctor. Then you and your doctor can come up with a plan of what medication to try next.
Some medications can actually make anxiety worse, especially when they wear off, so be sure to follow your doctor's instructions and contact the doctor if things don't get better or if they get worse.
As far as talking to your therapist, I would highly recommend asking for what things you can do when you get worried. Ask them about grounding skills, relaxation, mindfulness, thought stopping. These kinds of things can be started in therapy at the very first session and can help just as much as medications (and with no side effects or rebound symptoms! :))
One thing that helps me is to do 4-square breathing. It means you breathe in for 4 seconds, hold your breath for 4 seconds, and then breathe out for 4 seconds, and just keep repeating that. (4 times.) This breathing exercise signals to the brain and body that it is ok to calm down and it automatically sends signals to the heart and brain to slow down and relax.