Sort of confused about the ending of inception?

I think that at the start how Cobb got washed up on the beach then he got taken to Saito, that part was when he was trying to bring Saito back from limbo which is what we saw at the end of the movie, so basically the whole movie was showing the events of how Cobb got to rescue Saito. Am I even close? lol. also the ending I think it could be real because he got saito back from limbo finally, and the totem was mal's so it wouldn't work for him anyway so how is that a good indication of whether it was real or a dream?