Trans is a pretty inclusive term; it doesn’t just apply to the giant male-to-female or female-to-male cases. It can (but doesn’t necessarily) also apply to people who are non-binary, intersex, gender fluid, etc.
Here’s a decent explanation of what “Cis” (vs “Trans”) means, and since that definition does not apply to me (surgery was performed on me to forcibly conform me to male “norms”) that’s why I identifty as (kinda-sorta) Trans.
(I have some issues with how it’s worded (e.g. mutilation) and it’s a bit defensive, but it still gets the point across.)
This is an important part of my identiy because it is the source of my chronic pain and disability. If it didn’t impact my life so drastically, I would probably ignore this aspect of my life. But it does; so I don’t.
(This doesn’t mean that other people who have had a similar experience “ought” to identify as Trans–this is an identity that many don’t feel comfortable with, and it should not be forced on them.)
Cis is not a slur. And Trans should not carry stigma.