Living with Bipolar Disorder doesn't necessarily mean you're happy and loving one second and pissed and violent the next. It means your moods cycle (sometimes quickly, sometimes slowly), usually from DEPRESSIVE to MANIC.
In a low, DEPRESSED state, you sleep a lot, cry a lot, feel really low for no apparent reason, and begin to hate everything about life.
In a MANIC state, you can go days without sleep. There's thousands of thoughts racing through your mind at any given moment. You'll make rash decisions and enjoy gambling and living on the edge. You want to work on tons of different projects at once, sing, whistle, dance, play. You excel at work and appear almost as if you're on crack constantly.
Some people with bipolar lose touch with reality completely and experience excessive grandiose thoughts with delusions and full-blown hallucinations.
So, let's cut to the chase: if you're kinda happy at 2:00 PM and sad and angsty at 2:25 PM, you're probably just an emotional teenager or a hormonal adult. You may have a much less severe form of bipolar, or perhaps even Cyclothymia, but chances are, you're not suffering from full blown Bipolar Disorder, neither BI nor BII. I'm not saying that you must fit my examples perfectly to be bipolar, because everyone experiences disorders differently. But don't jump to conclusions because your moods change. See a doctor or a psychologist.