Thanks for all the responses. The bonnet has been sitting in my closet for the past ten years so I'm not all that upset that it probably won't get any smaller (no matter what I do). MacMillan seems to offer the only true option for changing the size of my bonnet but I'm not sure I'm willing to put in the time or effort. Like Brian said, the bonnet is historically correct in terms of size. I just never really liked wearing something that hangs over my entire head like that. It definitely looks like a costume or garb. I was just hoping that it would be more versatile so I could also wear it with my modern highland wear. Since that doesn't seem possible I guess I'll just have to join a Jacobite rebellion reenactemnt group!