I think it's better to say i "have" bipolar than i "am" bipolar, because it's not the only thing i am. You wouldn't say i am cancer or i am diabetes, so i don't think it should be different. It might seem nitpicky, but i think it's an important distinction. It's only psych diagnoses than are phrased that way to define a person, and only the most stigmatized ones - you say i am an addict, a schizophrenic, or a borderline, but i have depression or anxiety. Interesting isn't it? I'm trying to change the language i refer to myself with because i am more than just bipolar.