F - Am - G(with 13) - Em; C major is not a chord in this song.
The transition to the second half of the song was quite inventive and changed things up a lot; I wish it happened more often with different kinds of changes. You clearly know how to make good chord changes, I think it may be to sparse a change. For example, the times you do it in the end are better.
Whenever you go from the second progression of the song back to the first you do this really awkward transition from D major (the dominant of G) to F (which has no F# in it like G does). It sounds forced.