A big reason that drove me was that I have a micropenis.
Fake. There are no "reasons to drive someone" other than their internal gender, this sounds like something a cis personsomeone who thinks being trans is a choice would say.
Edit: For clarity, I'm not speculating on whether or not the OP in the post is trans or cis, I'm saying it doesn't sound like a real story because it sounds inauthentic to the trans experience. A trans person could easily think this up, like anyone can make up a story that is close to their experiences, but since it isn't real it doesn't really pass scrutiny.