Bench pressing 1.5 times your body weight means that, pound for pound, you're stronger than most guys in the gym.
Here's how to lift bigger plates:
1) Pull the Bar Apart
As you lower the bar, squeeze your shoulder blades together and try to "pull the bar apart," then maintain this tension while you push for more force.
2) Vary Grip Width
Alternating among wide, narrow, and normal grips allows you to focus on both prime and mover supporting muscles, which can help you break through sticking points.
3) Superset with Bentover Rows
Beef up your lats, which are key to moving the bar, with bentover rows between bench-press sets.