I agree with @Skeezyks, @Rive1976

What you describe sounds like a different kind of alternate who maybe uses humor at things like that to deflect from the pain that maybe another alter might feel. It is a defense mechanism of sorts, not necessarily indicative of a personality disorder, and certainly not in line with the emotion dysregulation that takes place among BPD, as described in the link that Skeezyks provided.

The best place to get all these questions answered is your therapist, or a trained psychiatrist, but they will need to believe in, have training in, and understand DID in order to properly assess and diagnose you, as well as help you.

I'm sorry you are going through all this. I know it must be scary to wonder what is going on.