Wow, you really gave this one some serious thought. Good for you for being so introspective. Often diagnosis change and it's because of the very reasons you've stated: Overlap and similarity in symptomology. However, over time, and with the help of a good pdoc or therapist, the correct diagnosis usually emerges. Also, I see that you are a teenager. From what I've heard, it can be very difficult diagnosing complex issues in people of your age group mostly because you are growing and changing and the clinician has to also examine the possibility that some of this may be attributed to normal and/or expected phases of psychological development.