The PP is right on the money. I had this problem with ds too, and although it's the opposite of what most people go through it's still hard. I did all of the above mentioned, but the only thing that really worked for me, was doing this for a few days to tell my body to produce a little less.........
Day one, feed only off one side, and alternate all day.
Day two, three and four, feed off one side 2x in a row.
If you don't see an inprovement, then just pull him off when your letdown first happens, and let it soak in a towel for a moment. Also, try not to let him comfort suck for a while, and when he is done, then that's it. By having him suck even when he's not that hungry, it's telling you to produce more.
The upside of this, is in a few months, when his demand is for more, you'll have it, and he will also get used to it. Make sure you burp him halfway or maybe more until he does get the hang of it. I would lay off pumping for a while, too. Good luck!