I agree, you should be talking to your treatment providers about this and ask them to put it in layman's terms. Sometimes it's hard to understand exactly what they're saying.

It's possible you could be misinterpreting what they're saying. It might be that you don't have DID or BPD or any other things and just have PTSD,cptsd as they're calling it. You may be assuming it's DID since you have alters but that's not always necessarily the case. Just the same as dissociation is and can be a part of PTSD but it doesn't automatically mean a dissociative disorder. So it's best to talk to the ones that are treating you so you can understand better.

If CPTSD was a valid diagnosis I know that's what mine would be but since it's not I was diagnosed with PTSD.

Let us know how it goes if you talk to them more about it.