If you really want to know more I would ask all of your professionals to show you the cptsd criteria in their diagnostic book.

Just as in the US, Australia used DSM 5 and ICD 10 and neither of these diagnostic books includes cptsd as a valid diagnosis. There is talk that ICD 11 will include cptsd but it has not been released yet. It will be published later this year.

I tend to question a lot of what your professionals have told you. Although different issues can have similar symptoms I do not see cptsd (again not an option as an official diagnoses in our countries) as an umbrella term for all the things they say it us.

Beside the fact that cptsd is an anxiety (stress) disorder and not a personality disorder. DID is also an anxiety disorder but it has very specific criteria to meet as a diagnoses. Although people with cptsd may happen to also meet the criteria for DID or BPD, it is not an umbrella term that includes all of those other disorders. If that was the case it would most definitely include MDD as well but you state that your professionals have given you a separate diagnosis for MDD.

DSM-5: why all the fuss? - Health & Wellbeing