I am NOT a proponent of BabyWise, and there are a few reasons why. You only have to look to our own eating habits as adults to realize my first reason. Even as adults we have varied eating habits, times, hunger levels, etc. We don't eat every 3 hours, so why should we expect our babies and children to?
Trust me, I definitely understand your strong desire and NEED to get everyone on a schedule that helps you sleep more because sleep is so important... not just to parenting and every-day function, but sleep also makes milk.
I want to let you know that your son eating from only one side at a particular feeding is normal as well, just as adults snack during the day. There are many factors to consider when you're exclusively breastfeeding. He may eat on both sides at one feeding, then only on one side at the next, and so on. And it may vary from feeding to feeding as well as day to day.
I also agree with the first poster when she advised about growth spurts and baby nursing often to increase your milk supply to go with his increased demand. If you put him on a schedule, your milk supply could suffer, and you may ultimately end up weaning earlier than you want to. Breastfeeding - especially exclusively in the first 6 months - is ALL about supply and demand. The more milk that goes out, the more milk is made. From what you say you're currently pumping, it sounds great! 4-5 oz is awesome!
When it comes to pumping, unless you're getting ready to go back to work soon or trying to build up a supply in the freezer, try to limit your pumping sessions to a 2-minute session just to relieve the ache and pressure in your breasts. You're at a critical stage right now where your supply is finally regulating to what your son is demanding, and if you don't need the extra milk, you pumping is going to send the signal to your brain and breasts to keep making all that milk. The cycle will continue.
In the future, if you have any questions (however small it may seem to you) about breastfeeding, please feel free to call Nursing Mothers Counsel at (650)327-MILK. You can talk to the counselor on the phone or be referred to one of our peer counselors for more extensive one-on-one counseling. We're non-profit, and we provide our services for FREE to all breastfeeding moms at all stages, prenatal through toddler years. You can also check out our website at http://www.nursingmothers.org for lots of info and worksheets! Enjoy your little one!