The Bench Press is the quintessential exercise people perform to get a bigger chest. There's no doubt that the Bench Press is an effective upper-body exercise, but you must perform more chest exercises if you want to get bigger and stronger pecs.
To stimulate chest strength and size gains, you must hit both the pectoralis major and minor from different angles. The best way to do this is by adding incline and decline pressing exercises to your routine.
In addition, it's important to perform similar variations of the Fly (flat, incline and decline). Flies recruit the pecs through an adduction movement (pulling arms toward middle of body). Although pressing motions work the chest, they do not activate the pecs as much as Flies. (Learn how to perform the DB Fly.)
Finally, if you are having trouble making gains, try substituting bench press variations with Push-Ups. This staple bodyweight exercise improves your chest strength while also building joint stability and core strength. They will prepare you to lift heavier weight when you get back under the bar. (Learn about the benefits of bodyweight exercises.)
Granted it will take time for your chest to grow. If you are like me, the chest is your weakest and most problematic muscle group. With this programming, you will be focusing on developing a lean, evenly built chest.