Between you and me and everyone else who's reading this, I'd bet that EVERY SINGLE ONE of us has nursed/fed a baby to sleep more than once for the sake of our own sanity.
Sometimes you gotta do what you gotta do.
You might be at the time now where more frequent nursing for a little while will up your supply so that feeds every 4 hours or so WILL be enough for him. Meanwhile, you can tweak the routine for a while so he's sleeping every 4 hours, even if he's eating about every 3, if that makes sense. In other words, a strict EASY pattern might be out the window for a day or 3 while you work out the new "rules."
He might be going through a developmental leap, working on a new skill, and the world might be too darned interesting to sleep right now, dammit, even if he IS patently tired. A slow wind-down from his first sleepy sign that takes maybe an additional 20-30 minutes before he goes to bed might help extend his Awake time and help shift gradually rfom 3 hours to 4 over the space of maybe a week or so. I remember we had to extend Josie's Awake time gradually; we ended up doing it around 5 minutes a day to keep her up long enough to make the shift, which made her naptimes much more predictable and easier for all of us. (She was doing short naps, which is a whole other issue, but the shift from 3-hour to 4-hour was part of the equation.)
Good luck and keep us posted. If he gets dependent on nursing to sleep, it's posible to wean that, but like I said, sometimes you have to bite the bullet just to save your sanity.
