OK, I finally understand this. I've read it over and over in the manual, but it never registered. I guess I was used to adjusting the OPV on previous machines. It's dangerous when you already understand something and don't realize you are wrong!

So I undid what I did and set the OPV back to factory settings, which was to drip at 11.5 bar of boiler pressure. I then adjusted the brew pressure using the adjustment on the actual pump as EricS mentioned. Working perfectly now. Thanks!