Yeah that... does sound sort of in the same ballpark.
I would say that is... potentially concerning, but I am not qualified to make a diagnosis.
You being aware that you are doing the sort of ... 3rd personing of yourself... that does not mean you are not depersonalizing, not derealizing.
The fact that you are aware, I would think that would actually narrow it down more precisely to being depersonalization.
The main thing is a sense of identity so weak that you basically just invent another one on top of it, if that makes sense, that just sort of observes the first identity, or as you say, you just make up a new one and pretend to be that person.
On a less clinical note, I am genuienly sorry to hear that and would offer you a hug =(
I have been quite depressed before, and ... yeah, hug.
It sounds like you've been through a lot of trauma.
For what its worth, you are still here, and some layer or level of you is still typing out your messages, so... you are still here.