need to be doing both dumbells and barbells when training chest as they use slightly different muscle groups, dumbells require greater balance hence why arent able to lift as much with them.
also, dont do the exact same chest routine every week. if u are doing flat bench then do incline dumbells and vice versa etc. incline is also very important as it focuses a bit more on ur delts which aid ur flat bench as well.
should aim for 4 sets on each routine, preferrably with another set for warmup on something light. mix it up by doing pyramid sets, drop sets and super sets as well.
try one-armed dumbell presses as well. u wont be able to lift as much, but u will not only do ur core but give ur entire chest a workout in trying to balance it. chest press machines also help as u can go heavier on them and even just do negatives to get more time under tension of ur chest.
flies should be done as well but make sure u dont rip ur shoulder out. cables should also be done from either above shoulder height, at or below. use the bench as well at flat or on an incline with the cables to do flies as well. pushups between sets also helps.