Simple, go to the side that's higher, get a mallet and WHACK, WHACK WHACK! LOL!
Sounds like you have to adjust the hood height, not the bumper. Loosen the hood latch attached to the frame on the higher side (mark position first) and adjust down. Retighten, then adjust rubber hood stop down a bit. Close hood and check alignment. Repeat as necessary. When you get it to the adjustment that makes you feel comfortable, close the hood and wiggle it up and down to feel the play. If it's too loose, bring the bump stop up a bit to get rid of the play. Caution: Always make sure your hood does not rub the headlamp housing.