Looks like you've got it pretty well right. If it sounds right...
At the start of the thread I had no idea what you were playing. There are lots of good folk dance tunes and songs from the British traditions that don't need complicated chords. There are also more complicated alternative chords that you can use, but don't have to, and usually can't on a melodeon. They are popular with piano accordion players who like to use them just because they can...

Anahata