you did waste a bunch of money. I can't remember the name of the thread, but I wrote to Cubanito, who was complaining he ate a bunch but could not gain weight and explained what I did one summer to gain over 20 lbs drug free. If you can't find it let me know, and I will post it again. But it involved eating 2 dozen eggs a day, steak, potatoes, ham, cheese, a can of chicken, and some other stuff every day. Eating 5 or 6 meals a day, each one of which contained as many calories as you are probably eating all day right now.
Suffice it to say, you are not eating enough. I don't care how much you think you are eating right now, or how much you are actually eating right now. It is obviously not enough. If it was enough, you would be getting bigger. Eat more, eat more, eat more.
Nothing they sell at GNC besides a good multi-vitamin is worth buying. Good cheap foods are ramen noodles, I used to eat a bowl of ramen noodles with a can of chicken or turkey for a meal. Cost is around 2 dollars, and you get about 40 grams or more of protein, some good complex carbs, and not too much fat. Ground beef is good. Eat hamburgers, hamburger steaks, nachos, burritos, tacos, tons of ways to use ground beef. Eggs are cheap and very good to gain weight. If you are not lactose intolerant milk is very good for putting on weight.
You have to completely change the way you look at food. You have to eat until you are sick. Wait 5 minutes, then take a few more bites. You literally have to gorge yourself to the point that you stretch your stomach out to where it takes more and more food to feel full.
I graduated from high school almost 10 years ago at 5'8" and 155 lbs. I weighed 230 at the same height last night at the gym. I am not a naturally big person. I have had to work, and eat extremely hard to put on size. You can do it, but the work involved is a much higher price than most are willing to pay. On the upside, once you have put on some good size and made it past the 200 mark, and get past 25 years of age, you don't have to eat nearly so much to maintain or gain in size.
Good luck and hope this helps.
B