This song goes to the chorus right away after the first verse. More unusual is the fact that the chorus then repeats! There's only been one verse, but we're hearing the chorus twice. It has different words the second time.
After that, there's another verse and then it seems to go to a bridge section ("Today I love you more than yesterday" etc.). A repeat of the chorus with a derivation on its first set of words follows, but then what? The bridge repeats here?
Looking back at this point, we can see how those three choruses with the different sets of words are actually functioning like verses in relation to the bridge, which frankly sounds kind of like a chorus itself and is indeed functioning like one now in the way that it's repeating.
This notion seems to be borne out by the fact that Lennon then proceeds to use a derivative of the first part of this bridge/chorus as a refrain line that repeats four times for the song's closing.