Eddie, there are many songs that have the same progression all the way through. Usually they have some kind of bridge in there though.

To me key changes are overused by composers. There should be an emotional need for them, even in the commercial world of music, very few songs have key changes.

Bridges or pre choruses are much more needed.

I see this song as more low key, than hit-esque... if thats a word.

I enjoyed the listen. Seems you enjoyed doing it.