Good physique; try new things but at the same time don't get hung up on the idea of having to have perfect symmetry because sometimes it's neither possible nor important.
Change the variables, try new variations for a few weeks each & see which help. Start with variations on what you're already doing-dumbbell presses instead of barbell, try varying the incline on incline presses.
Then try some other exercises, such as weighted dips or pushups, or pec deck. On dips, leaning forward or backward will make a difference as to which part of the upper body is emphasized, as will doing them forward or turning around facing the other way. Use some non-lockout reps here at the end of sets, and also try partials in which either the bottom or top part of the ROM is removed entirely.
Try also a period of time in which the incline work is entirely removed, leaving just presses & flys. Concentrate completely on getting the weight and reps up, on less sets, rests of no more than a minute between sets.
Supersets, trisets, non-lockout reps as mentioned, rest-pause, some negatives - cycle through the usual suspects, each for long enough to know which work the chest better. Twice a week training at least, even try thrice weekly for a minute.