I have pretty good chest development but when i am posing my lower pec around my nipple and working toward inside my arm is a tremendous amount softer than the rest. I feel as though im not even hitting them. My inner, upper and middle areas of my pecs are very sore after workouts but my lower aren't. I usuallly do flat bench, incline flys, and either cable crosses or wide flys. Feedback please what am i not doing?