All the best.
It can be daunting, but it's not too bad. They are there to help you, and in order to do that, they need to know what it is you are feeling. If you can remember any triggers, or have an idea of when you cycle, it also helps. If you are on any other meds (Psychiatric or other, you need to notify him), He also needs to know of any major circumstantial issues that may be affecting you, any past or present major stressors.
And then you need to describe your emotions as best as possible.
If you can, maybe make some notes before you go, so you don't forget anything.
Let us know how it goes