Yeah, I've been diagnosed with it too. I am seriously doubting that my symptoms are severe enough to warrant a mental illness diagnoses of Bipolar I disorder.
Having said that...
It is very common for people with this disorder to doubt or refuse to believe they have this illness.
In order for anything to be an actual "illness" or "diagnoses" (every one has minor symptoms of a mental illness) it has to be severe enough to be very distressing (subjective) to the individual, interfer in social, work, or school--causing one to be reprimanded, fired or just quiting because you can't handle it anymore.
So, ask yourself these questions and maybe you'll answer your own question.
Good luck! I hope you DON'T have it!!!