Jenn, (I also pm'ed you)
No you are not a "bad PMAN".

The alum chapter I'm currently pursuing knows that those of us in the workplace/careers etc have obligations. And ditto to what Kelly said, due to your line of work and the 12 hrs shifts give them your schedule for a 2wk period via email and / or follow up w/ a phone call.
Keeping my fingers crossed that you can make it to the next events of group 1 and group 2! Its okay to vent and enjoy your Honeymoon next month.