Not a solution but will eliminate one of the possibly
Train back first see if your fatigued on the chest portion of the workout?

Maybe the pressing group of muscles is just used to more of a pumping than your chest?
You could try limiting the range of motions on bench ect so not to use the tris so much or super setting flys at the corresponding angle to your presses (incline flyes to incline presses) or the other way around.

But hey youve got more years training on me just some ideas good luck!