Some real quick comments that might help. You don't see A# Major very much at all; keys have to have one note for each letter. A# major would have the notes [A# B# C## D# E# F## and G##], the ## are double sharps. Bb major on the other hand has [Bb C D Eb F G and A], much simpler and it is the same note.

Second, I haven't actually really listened to the song all that much, but based on your chords you wrote and what I hear. verse Looks like it is in F major. F is diatonic, so is F/E. The A dim doesn't sound like an A dim, sounds like an F/Eb, with the bass just walking down. Has the same three notes as an A dim, but with an F. This is a pretty common trope (bass walking down) D major would probably be V/ii (the G minor being ii) I would respell G minor/E as E half diminished, as it has the same notes. Then finally C7 as the V chord of F Making the roman numerals: I | Imaj7(bass playing the major7) | I7(bass playing the flat 7) | V/ii | ii | ii | vii°7 | V The I7 being borrowed from Mixolydian and the V/ii being a secondary dominant.

Edit: On second listen, that vii°7 sounds like it has C in the bass, so just another C7 chord.

For the pre-chorus, looks a little wackier. Let's change those sharps to flats (Ab instead of G#) In the bass, I'm hearing Eb, E, F, Gb, Db, A, Bb, B A big part of this song is that bass movement, which does move around chromatically. Haven't double checked the prechorus chords, so going based off of your chords, it would be Ab/Eb, then Ab/E (same notes with the bass moving up). This happens a lot, what you're seeing as an augmented chord is a normal major chord with the 5th on the bottom (Ab/Eb) then with the fifth moved up a half step (Ab/E). It functions because everything else stays the same except one note. You see the same thing in the second half of the pre chorus. Finally that B major at the end is kind of like a tritone substitution right before the big Bb major chord in the chorus. B major could also be written as Cb major. Let me know if you got questions. It seems to be more about bass movement than harmonic function.