Your best bet is just to be you. Pyschologists and psychiatrists ask questions that are "testers", questions that are mean to see if a person is answering honestly. When I took my written test and had my 7 hour interview, I was told by the psycologist afterwards that they do this. Its better not to try and second guess them or wonder if you have answered the way you think they want you to answer.
If your psych has worked with transgenders, he or she will be able to tell if you are a good candidate. I won't tell you not to be nervous, because that would be impossible, but just be upfront and honest, even if you think the answer is not what they want.
Good luck. I really hope you are passed as a good candidate.
sam1234