Lugar,
Building mass/strength requires one to challenge each muscle group with each training session. You will never know if you're stronger over a period of time unless you stick to your game plan. Mass is about appearance, where strength is about numbers. You don't wear your bench press figure on your shirt, so why sweat those numbers.
Also, building mass is not always about weight, sets, and repetitions. Building mass is a regimen that includes training, diet and rest. You can't just do one of those three and expect greatness at the end of the day.
Keep at it.