It's not uncommon at all to be on multiple medications for Bi-Polar. In fact, my mother and I often place bets everytime I go see my Pdoc because 9 out of 10 times I come back with yet another prescription. Just for my BP, I currently take Wellbutrin, Lexapro, Klonipin, Lamictal and Rozerem. I also take protonix, triamterene and topomax to offset the side affects brought on by this combination of drugs. It would be nice if the pharmacitical companies could come up with one pill that does it all but that's just wishful thinking. It all depends on the individual and their specific needs.
I do have a brother who also suffers from BP and he has been stabilized by using the exact same drug regimen as me. Not sure if it's because we are both from the same genes but it makes sense.
So believe me, you are not alone with the multiple medications. Along with my above medications, I also take asthma medication and soon RA medications. When I travel I have to pack an extra suitcase just for my meds.