I do plenty of those, heavy weights, slow reps, the works, but it's not doing anything for me. :shrug:
Are you doing flat only, or incline-flat-decline?
Strictly bar, or are you mixing it with dumbbells?
If you do plenty of those, you just may be doing too much. You may want to give your body a break from the heavy weights for a couple of weeks... if you feel you are "losing it", it would be basically on in your head

, but you can do push-ups just to keep that pumped-up feeling. Then when you hit it again, give yourself some more time between chest days, and don't do the same exercises week after week. Do something like one day is incline-flat with bar, the next week is decline with dumbbells, the next week is incline-flat with dumbbells, and so on. Whatever it is, just don';t do the same thing week after week.
As for the OP, I am old now

, but back in the day, the best I ever did, was 4 one-handeds... now, I may be able to do one chin up, and that would be with a LOT of body English