Disregard every post that calls for you doing more volume. You are doing something fundamentally wrong most likely and doing more of it is not going to fix your problem.
I agree with that post about getting bigger. Getting bigger and getting stronger are two entirely different realms.
This is what I do when I am trying to gain muscle mass.
You have to feel the muscle work. The problem with this method is that most people pick a certain weight and begin the set feeling the muscle, then they fatigue and end up squirming the weight up. If you cannot stick with feeling the muscle and basically squeeze the weight up EVERY SET of the exercise the weight is too heavy.
This is a whole different concept because you are not lifting weights based on how many times you can lift it, you are lifting weights based on a weight that you can control the entire set, if you start to go too high and end up with a weight you are just repping out without controlling it, you will screw up the entire progression of lifting this way. I wouldnt try to use this method with barbell bench, barbell military press, Bent over Row, or barbell back or front squats. These exercises are just too difficult to do with this method.
And you would have to use a weight too light to get the benefit of these exercises IMO, also you will get a greater effect of this method using dumbells and cable exercises because of their freedom of movement.
Also, it usually takes a few weeks for your muscles to really adapt to using this method so that you will feel the exercises very well.
I used to notice that when you are dehydrated you will underperform much more when lifting in this way than traditional strength training, so hydration is a must.
Alot of your improvements in muscle mass using this method will come from just being able to do it. For instance if you usually rep 50lbs on dumbell bench for 3 sets of 10 reps, when using this method, you will probably start being able to do 3 sets of 10 or 12 10 8 etc.. with 35 to 40lbs at the most. Like I said you will probably not start to feel the movements really well for a few weeks or so. During this time, keep going slow, squeezing the weight up about 2 seconds and emphasizing the eccentric for about 3 seconds.
Until you start to feel the pump and your muscles squeezing the weight up do not increase the weight. When you start to feel this, you can increase the weight as long as you can keep the temp and can feel the muscle.