I identify as a transman. There is no space in that word for me.
This is somewhat unusual among trans people. In general, it’s convention to call people like me trans men, not transmen. In fact, when talking about the group in general, or an individual other than myself, I use the space. The same applies for trans women – I use the space unless a specific individual prefers no space, which is pretty rare. I use a space for cis men and cis women as well, to be consistent.
The reason for this space is that most people identify as men or women, and trans or cis are a modifier. Being transgender is usually a statement about someone’s history, not an intrinsic part of their gender identity. A lot of people feel really strongly about this, which is why the space has become the standard convention over time, although this was not always the case.
My experience is somewhat different than most people. I am not a man, with a trans modifier. I am a transman, as a complete gender. I do not separate my transness and manness – they are deeply connected for me, inseparable.
The fact that I experience my gender identity differently than many other people does not mean that I have any disagreement with them over the space. It seems pretty clear that for most people the space is important, and that for many people their complete gender identity is man or woman, with a transgender or cisgender history. My gender is not better than anyone else’s – it’s just different. It’s just mine.