I've wondered about this when reading some of your other posts, but wasn't sure if it would have been out of line for me to speculate. DID can mimic the symptoms of many, many other mental illnesses and disorders. Without integration, I think it's almost impossible to confidently diagnose other illnesses/disorders alongside DID. Compartmentalization can produce mood swings, anxiety attacks, depression symptoms and even psychosis-like experiences via flashbacks and layered perceptions.

Something else to consider is that some research studies show that dissociative symptoms are very common in bipolar disorder, as the disorder itself can be so overwhelming as to trigger such strong coping mechanisms. DDNOS from childhood trauma combined with bipolar disorder can present very much like DID.

A sure-fire way to detect DID is periods of amnesia. If you have large chunks of your memory missing, and/or lose time throughout the week/day, this strongly suggests DID. And if you have DID, DID itself can, again, cause tons of symptoms that can present like many other illnesses/disorders.