You might want to try stropping with a little more attention to keeping the [I]edge[I] of the razor in firm (not heavy, but not light) contact with the strop's surface. The goal in stropping is to polish the edge smooth and also straighten the edge. After stropping, you should notice a big increase in sharpness. Don't worry about going fast; slow and careful works just as well. Only a few laps (around a dozen or so) are needed.