Having been born in, and having a parent who was born in, and raised outside of Los Angeles, I always have to shake my head a little when people put the South Bay into LA or try to lump all of Southern California into LA.
I was born in Fountain Valley & raised in Norco, my father and mother are from Long Beach. I have always been almost painfully aware of where Los Angeles actually is.
It would take me forever to actually get this totally correct, but here's a sort of quick outline of Southern California and the part of it taken up by Los Angeles. If you really wanted to measure by land mass, the OC is probably about the size of LA & NY put together.