Try dialing the slim back to #3 for a starting point, the higher the number the more aggressive the slim is. The two biggest factors for inducing razor burn are too much weight on the blade and a bad angle. All you need is the weight of the razor resting on your face while you steer it around keeping the correct angle as you go. To get a good starting point for angle to use, rest the top cap of the DE on your cheek with the handle straight out parallel to the floor. Next, rotate the handle downward slowly till you can just start to feel the blade. When you are there you have your starting angle, you can adjust from there as needed. You have to try and maintain that angle buy moving the handle as you go to match the contours of your face. The head of a DE does not pivot like on a cartridge razor so you have to do it. I'd stay with the lower setting and one make of blade till you can get a shave without razor burn. Everyone is different in how many good shaves they get out of a blade and for me that is usually around 5 no matter the make of the blade. Good luck on your next shave.
Bob