Wait...this is only tangentially related, but still:

...I am anxious.

...I am depressed.

...I am fearful.

...I am irritable.

So far so good.

So to me, it means that - continuing the pattern:

-- I am hypomanic

-- I am an insomniac

-- I am agitated

-- I am restless.

the thing about the word "bipolar" is that it was a politically correct word that replaced "manic depression", and as such the word does not by itself describe any particular mood but instead describes the volatility between different mood phases. So the word is artificial, and that allows us to play with "I have" vs "I am", but in reality, neither "I have" nor "I am" really goes well with "bipolar". But that is true of many words and terms that were borne out of the desire to be politically correct - the invented words or word combinations are not particularly mellifluous and often fit poorly into English sentences.