Dropped from an untrained 15.1 to 13.3 in about 3 months. Two years later (from the 15.1) I was running 11.9.
I'm guessing your pretty young (how old are you by the way), and judging by your 145lb bodyweight your lifting for size hasnt gone very far. If you can run 11.8 (a legitimate 11.8, which I'm not sure it was by reading the description of how you got that time) relatively untrained for track then you would probably do well in the sport. As for dropping a full second, that really depends on you, your genetics, and how you train. But you WILL drop your time if you train hard and you train smart.