No, when you have a disorder, in your case Bipolar Depression you do not have to have every single charateristic. I have Bipolar Depression also, and I don't have the racing thoughts. And I have some of the other symptoms in varying degrees. This also would apply to you & your brother.
The same with BPD, Borderline Personality Disorder, there are 9 characteristics - not that a person MUST have every single one - no, and not to the ultra maximum 100% degree, rather ppl have various degrees of the disorder. It's general knowlege for the public. The best idea is to see a therapist and /or pdoc for a diagnosis and they can suggest the best help for you. I hope this relieves your mind somewhat.

Holmes