Not sure if your really that concerned about increasing the BP or just curious. Even if you say you want to join the 2 plate (225lb) club. Also get the impression that you use DB's or machines on just about every exercise. Judging that from the fact that you did not know the weight of a standard Oympic bar. If you do want to increase the bench than you have to train the motor units involved in doing the actual BP. That means more reps on the lift it's self. The lift should go up fairly fast once you get use to doing it. Suggest also that you try the 3 hand position from time to time, all in the same workout. Wide grip, nearest the collars as you can. Middle, a little wider than shoulders. And Close grip, about 10 to 12 inches apart. 2 sets each. Seen a lot of guy's make good progress this way.
5X5's has been the standard for decades, producing both strength and muscle mass. If you gym has 1 1/4 plates (2 1/2 lbs total) than try adding them every other bench workout. Every workout if you can.
If you want a different approach than you might consider GVT (10X10's) for 6 weeks or so on the BP it's self. Will increase strength (motor units again...100 reps total workout) greatly and also mass. Should also expect a muscular weight gain. This would be the only chest exercise done for that 6 week period. Do a search on GVT or go to T-nation.com and search there. Good Luck.