I think you are overworking your triceps not your chest since you work your triceps with chest day, with shoulder day and with arms day.. try to design a routine where your biceps and triceps work only twice a week at the most.
you can do:
monday: chest (12 sets)/triceps (9 sets).
Wednesday: Back (9 sets)/ biceps (9sets)
Friday: shoulders 9 sets without traps and rear deltoids / abs
Saturday: Back ( 6 sets only ) Traps (2 sets) and rear deltoids (2 sets)
Sunday : rest or abs
this way you will be doing triceps twice a week and biceps twice a week (biceps works with back)