You can have symptoms of DP/DR secondary to many organic conditions and psychiatric states like depression, PTSD (dissociative subtype) ect. Dissociation in borderline is known. Depersonalization is a primary condition typically comes very sudden to stress, drugs, panic or depression. Most can say where they were, when it happen. It is a sudden brake in self-experience. There will often also be high level of anxiety, mental hypochondria about going psychotic in the first months to the outset. Because depersonalization as a primary condition is very under diagnosed and to many unknown it might not have been considered. You could also have it to a secondary condition.