I Beleive I Have Been Misdiagnosed For The Last 8

i beleive i have been misdiagnosed for the last 8 years with depression & anxiety another time told i was bi polar, & another time told i have borderline personality disorder. ..but after my cousin has told me about her symptoms of adhd shes being treated for, these symptoms also seem like they can be side effects of my disorder...do all these disorders share such similar symptoms? if so, whats the determining factors