I’m a long time musician that knows a little theory but I really do everything by ear. As an exercise I wrote a riff on guitar and then attempted to analyze it by creating a hookpad project to understand exactly what I wrote and also perhaps write new parts. I cannot add the chords the way I want to and I’m trying to understand why. Basically the progression starts with Em - Em7 - Em6 - cM7 - FM7sus4 . I think it would be in C major but for the life of me can’t figure out how to get the Em6 as an available chord. Any help understanding why would be greatly appreciated . Thanks in advance.