If you look at symptoms of other mental illnesses and personality disorders, you will see that many of them, almost all of them really, have symptoms that overlap. It is really easy to see a list and think the category applies to oneself. (That's why the cheesy simplified horoscopes in the newspaper work... think your horoscope fits you "dead on?" try reading the others on the page with an open mind... pretend that they are your horoscope... you'll see that MOST of them "match" you to a T. Its something that the human brain just likes to do... find patterns and force matches. That's also why we see animals when we look at clouds...)

Anyway that's why you have to see a doctor for a true diagnosis. Only someone really trained and objective can determine a proper diagnosis, and often even that is very difficult.

But the most important part is what others have said... now that you suspect you are bipolar, what is the next step? The only reason for these "labels" is to help others figure out what types of treatment we need to become and stay well. For that you need a doctor, whether or not you believe that you need a dx from him, you do need his help in battling this illness.