From such a short letter it is difficult to determine if PTSD is the correct diagnosis. It very well may be but dissociative identity disorder (DID) is also a realistic possibility. It is not uncommon for individuals to have both DID and PTSD. In fact, some studies have shown that among individuals diagnosed with DID, the majority have a secondary diagnosis of PTSD.
According to the Diagnostic and Statistical Manual (DSM) for mental health disorders the diagnostic criteria for a DID diagnosis includes:(1) the presence of two or more identities; (2) at least two of these identities recurrently take control of the person’s behavior; and (3) having an inability to recall personal information. Your specific symptoms include having no memory of your childhood; a history of severe abuse; a recognition of other possible personalities (often referred to as identity alteration); and time loss experiences. Generally speaking, your symptoms are in line with a DID diagnosis.
I would strongly encourage you to be evaluated by someone who has experience treating dissociative disorders or trauma. One of the main difficulties with DID, and dissociative disorders in general, is that individuals may be experiencing symptoms they are not fully aware of. This is why it is important to seek outside assistance from trained mental health professionals. It would also be beneficial to educate yourself about DID. A quick Amazon.com or Barnes & Noble search could help you to identify helpful resources.
While I cannot offer a reliable diagnosis over the Internet, I do believe that dissociative disorder is a possibility. A psychiatric evaluation is the quickest strategy for determining an accurate diagnosis and more importantly to guide you to effective treatments. I wish you the best of luck. Please take care.