I didn't read this whole thread, but right from the start you are setting yourself up for failure. You CAN NOT compare your metabolism to the like of anyone else. Everyone doesn't fill out the same way.
ME: Weighed 135 for YEARS...........
What I took: MASS XXX, and a multi enzyme dietary supplement.
What I changed in my diet: Nothing
I started out eating normally, then I would take 1 16oz shake mixed with water (MASS XXX), due to me being lactose intolerant. The MASS XXX adds about 750 calories to your daily intake. It also adds 50g of protein. After about 3 weeks, I had gained almost 6 pounds. I stll wasn't happy, so I added some 100% WHEY PROTEIN, which adds about 20g of protein per serving. I would take about 4 of these per day with 8oz of water. I think that this really did the trick. I don't know how long I was taking the combination of the three, but I gained almost 13 before I realized anything. If I were to guess, I would say that I did that combination over 2.5 months?
To gain mass, you have to eat BIG!
Also, make sure you have funds aside, weight gain can cost you a lot of money for supplements and shakes.