I "demand" FF fed my DS and it ended up being a disaster, he just ended up drinking less, more frequently. At about 8-10wks I changed to 4 hrly and we never looked back, I always made sure I was feeding enough so that we had 10 -20mls left over, and just upped it when he consistently drained the bottle.
It took a day or so of stretching his feeds (distracting him) but after that it was awesome.
TBH I dont see how you can overfeed a ff baby anymore than a bf baby, and i think being concerned about obesity a bubs so young (unless there is an obvious problem) is absolutely rediculous.
GL hon.