i have to second the 12 week growth spurt....definitely let him nurse as often and long as he wants...this will be a huge step towards getting your milk supply regulated..
Also, it sounds like you have a "snacker" baby.
My dd was like this.
She would eat and sleep in "tiny little packets"
instead of feeding, say., every two hours and then sleeping two hours, she did everything in tiny little amounts...nurse 20 minutes, sleep 10, nurse 30 more minuites, sleep 15, nurse 20, up 20, nurse 15, sleep30...etc..ALL day long
About drove me BONKERS
But, it is just the natural biorhythm that some babies have.
If you can accomodate, I would try...if you feel like you can't/won't, then you probably need to look into some type of gentle routine modification techniques.
Also, could your supply be on the low side? After the 12 week spurt, i started making more milk, and noticed a significant time in between feedings.. (like a whole hour instead of 15-30 minutes, not a huge spacing, but still....)
The 12 weeks mark tends to be difficult for some babies..depending on what you believe, some would say that babies are "supposed" to be born right around then, at about the 12 month mark of gestation, which is why so many changes hapopen between 12 and 16 weeks......babies younger than 12 weeks are possibly not really meant to be outside the womb yet, and their little bodies go through so much around the time they "should" be getting born.