Try getting some more sleep...
I'm a student with 21hrs of class for 17 credits and I work, Basically sleep deprevation made my workouts last year suck, I mean I was lifeless, and even thought the weight I used was decent there as no progress. Try taking naps before lifting this always helped me. Lets say class ends at 5 eat dinner then go to sleep for 2 hours, drink some cold water and go lift, you will feel energized in the gym....