@Jiemei0 You're in a tough situation in Santa Monica as historically they've enacted very strict rental rules. Airbnb requires all hosts to comply with local rules and regulations so my guess is that Santa Monica rules about short term stays would overrule any Airbnb policy. My advice is to go to the powers that be in Santa Monica and explain the layout of your listing to see if it fits their definition of a shared / private room.
Many cities have instituted these types of regulations because they fear housing shortages due to property owners renting out on Airbnb. Santa Monica, as I recall, has rent control, does it not?
Sorry to say, but you'll need to check with the authorities in Santa Monica to see if your listing fits their requirements. Part of living in paradise, I'm afraid!