I think being too prepared is a mistake for the initial few visits. The T will most likely start out by asking what brings you to therapy. You can give as much or as little information to answer that (and any) question that you like. Don't try to anticipate a diagnosis - tell the T what things you'd like to be different and let the T figure out the plan for you to get there. Most clinicians aren't that big on diagnosing. They'd rather deal with the person as an individual, rather than a set of specific symptoms.

Remember, if you're planning on being in therapy for more than a few months, you don't have to get it all out in the first session. It takes time. They don't expect to hear it all right up front. In fact, most long-term focused therapists won't even formulate a treatment plan until you've seen them a few times. Even so, not everything will come out then. I know in my case, we're working on things now that I never anticipated we would work on when i started seeing him a year ago. I don't know if he anticipated these things either, but I'm sure he knew right from the start that there was more than just the fairly superficial things I brought up in the beginning.

Use that first session to feel out how easy the T is to talk to, if you like his/her approach, and if you think this is someone with whom you can develop a relationship. That's the key, really. You want to leave that first session believing you "click" with the T or that you at least can get to that point.

And don't worry too much about the intake forms. I doubt any T expects to see it all there. Some things take a long time to bring up and they know it takes time to build that trust.