First, the most challenging topic was writing a letter to my future daughter.
Because I'd never thought about that, and I didn't know what to say or what I want = wanted about a child.
Then I noticed that I've never thought I could be parents = a parent.
I'm just feeling I'm still a student or something.
So that also made me know myself well.

OR
The most challenging topic was writing a letter to my future daughter. I had never considered what I would want to say to a child, or even imagined being a parent. I still feel more like a student than someone preparing for that role. This assignment helped me realize these things about myself.