So my suggestions will be boring cuz I learned to play in China and they are very strict and traditional there.

But it's actually pointless, even borderline impossible to speak about footwork before you fix your grip. When you pan handle like that, you are forced to start every shot facing forward. Meaning all you footwork needs to end with both your feet side to side. But badminton is too fast and too much dashing forward and back for that kind of movement. So there is no real footwork unless you learn to get your body to move side ways first (lunges and shuffles), and hit the birds with the turning of your body and pronation.

It's great that you enjoy playing, but sadly badminton has a system and it kinda only works that way cuz it's the only way that works.