Since I wear a tam o’shanter, rather than a balmoral (in my regiment, the men wore tammies and the officers balmorals) I have no suggestions to offer regarding the shape of the bonnet.
But regarding the bonnet badge, I notice that several members recommend wearing the badge over the left ear. I would not call this wrong, but in the regiment we wore the badge over the left temple. Consequently I still do.
I suppose different regimental sergeants-major interpret the rules differently, as can be seen with the prescribed position of garter flashes.
When I wore a beret (while serving in a training battalion) we had to wear the badge over the left eye, rather than further back.
Regards,
Mike