there's a huge wealth of information on bipolar disorder out there and if u read enough profiles of people affected by the disorder eventually you'll recognize yourself as being similar to these people, or not.
Mood swings are common to even healthy people. Time of the day, diet, menstrual cycle, life events all contribute to mood shifts. The difference is usually these small promptings don't contribute to making u want to lock yourself in your room for weeks at a time or alternatively, talk 3x your normal rate of speed, take on grandiose projects and desire several new sex partners/week.
Drugs can help. For me they don't and only make me feel ill. CBT ( cognitive behaviour therapy) helped a little. I'm considering getting into Buddhism simply because of their emphasis on emotional awareness and control - basically CBT on steroids.