I saw my psychiatrist for 4 years.. And, now, nearly 8 months after I saw him for the last time, I'm still wondering where the 'assessment' part of things was. Initially, we talked about about my past life and once he was caught up on that we talked about my day to day life and what my plans were going forward - there was never any signs of a 'psychiatric assessment' as I'm familiar with them.
Go along, be honest and know that most of us have messy past's that we think might stop us.. And yet here we are, on the road to transition, or far enough along it that we can call it done.