Do you hold yourself accountable to good reps? Are you really working at getting to full depth or getting your chin over the bar? When you add that extra weight, are your reps as good as if you took a few pounds off and focused on getting quality reps in?
Sometimes taking the focus away from the quantity of workout and turning it to the quality of those workouts can positively impact fitness.
Another question you may need to ask your self: Am I always staying within my comfort zone during my workouts?