Perhaps your problem is your workout frequency. Maybe u should try doing two 10-12 set chest workouts a week. Also include flye movements and natural pullups in that. I know plenty of people who've had to adjust their chest routine frequency in order to see results.
In addition perhaps you should stop training arms to see if this improves your chest results, and make sure dont train them for AT LEAST 48 hours before your chest workout.
Just a couple ideas.