Take a day off - enjoy a warm bath, pedi, and treat yourself to a nice lunch.
Co-worker would piss me off too.. but you aren't her boss and they let her get away with being a lazy slacker... don't let that take away from your good work ethic, I'm sure you are noticed and appreciated.
The table foods thing, I would try to let it go unless you are afraid LO will choke and your mom won't be able to handle it. Puffs and cheerios are practically the same thing.
People on the holidays - stick it to DH to entertain and watch LO while you hide in the kitchen ALONE! Then go to the grocery store/butcher shop and pick up a cooked thanksgiving dinner with sides... don't kill yourself over it.
The hormone thing, I totally get. It sucks! Mine were pretty close back to back, and even this time it's still a little close... I have been over taken by this other being. Short tempered, hormonal, mess. Hang in there!