I think I know what the answer is, but I'm going to post anyway in case there's something I've overlooked.
EBF ds is 17 weeks and has for the first time ever begun to empty both breasts at a feed (I've always had more than enough milk). He's wanted more (when there hasn't been any more) but not to the point of screaming in hunger.
What's happening? General 4 month growth spurt and my supply will meet his demand or am I drying up? My boobs feel and look a lot smaller - back to normal size after being several sizes bigger.