It sounds like you were on the right track with pumping less frequently. I know that means discomfort, but every time you put up with discomfort, you reduce your milk supply just a little bit. It's going to take some time to tame the oversupply, so patience is going to be necessary!
You might want to try some of the tips on managing engorgement here, and maybe drink some peppermint or sage tea. They're supposed to be good for reducing supply. So is Sudafed, though I don't know how you're supposed to go about using it.
Since you have such an abundant supply, have you considered milk donation? There are lots of babies out there who could benefit from your oversupply issue!
I used to be an oversupplier, and I was going through the same thing; also considered donating.
Now my son is 7 mos, and I'm starting to have problems w/ undersupply. I would suggest that you not go overboard w/ dialing it down, and either donating some of your excess milk (but not all!) and/or buying an extra freezer to handle the rest. I'm looking at my dwindling supply in the freezer with a little more sadness every day...
I had terrible oversupply when my baby boy was first born, and I was pumping bottles and bottles of milk in addition to breastfeeding him exclusively. I thought it would never get better! But one thing to keep in mind is that your baby will want more and more milk as it hits its growth spurts, so your oversupply problems are bound to decrease over time even if you don't do anything!
Meanwhile, I agree with other posters - go as long as you can between pumpings, and try pumping only one side at a time. If you are painfully engorged, try pumping just enough to relieve your misery, without emptying your breasts. Donate your excess milk.
But also, don't work too hard to reduce your supply, or you may have to work to increase it later when your baby starts to really put on the pounds! As miserable as your current situation seems, I promise that it will pass, and you will be glad you kept up your supply so well! Oversupply is hard, but it is a blessing compared to having too little milk.
Hang in there!