Yea, you don't really list your diet, and I'm going to assume its the major issue. If you are trying to gain weight, you have to be on a positive caloric intake, preferably a massive positive intake. You are 160 lbs, so for a quick solution I'd say aim to eat 20-25 cals/lb. That's 3200-4000 calories, in balance. For your goals I'd say try a balance of 35% protein, 45% carbs and 20% fat. So that's about 280-350g of protein, 288-360g carbs, and 71-89g of fat.

Write it all down. For diets, this is key. Make sure you aren't missing anything.