I came tot he conclusion because I always thought i had some form of extremely mild BD, but doctors said no... then iw as reading the subtypes of ADHD and saw that the two subtypes resembled my own cycles where id be in one subtype or the other depending on the day (cycles over months), and then that got me thinking so i started doing research and found that there is a lot of overlap.
I am fairly convinced 100% of BD is just an extension of ADHD, just if we are talking Type II is a particularly extreme form.