I hate to be negative, but in my opinion if you have an arched back and your feet aren't flat on the floor, it isn't a clean bench to me by any means.
On a positive note, I'd probably go back to old fashion pushups. Try incorporating this routine.
Do a total of 50 pushups, but on every 10th pushup hold halfway in the middle for 10 seconds. Immediately after you get done, go into a handstand against a wall (to keep your balance) and do handstand pushups.
I stopped benching for about 4-5 weeks and did this routine every morning when I woke up and before I went to bed.
My max bench went up by about 45lbs. It worked for me, hopefully you'll find it helpful as well.