Amber, you may have it right. :) Since posting yesterday, here is what has happened:
Bedtime nursing: Thomas bites me before he's hardly started. I respond with a loud "no no!" and he freaks out and wails. He refuses to nurse anymore, but goes to bed (surprisingly) without much fuss.
Early morning nursing: Thomas bites me right at the beginning. I respond "no!" and he cries and refuses to nurse. He goes back to sleep in his crib for another 30 minutes or so.
Morning nap nursing: Again, Thomas bites me before really starting (I wonder - perhaps I'm not letting down quickly enough and he's frustrated?) then cries when I say "no". He takes his nap without nursing and without fussing.
Afternoon nap: He falls asleep in the car and transfers!!
At this point, since he has missed FOUR nursing sessions in a row, I decide to try nursing him when he wakes up. He nurses happily on one side, and then cheerfully pushes me away.
I am starting to wonder if my milk supply is just drying up. I didn't expect that, because I thought that nursing as frequently as we were would prevent losing my supply. On the other hand, maybe this is my body's way of protecting the pregnancy - at 10 weeks along I've not gained any weight, which is unusual for me. Maybe nursing and gestating is a bit too much multi-tasking?