EAT MORE FOOD!!
6 Meals a day (Every 3 Hours)
Minimum of 1 gram of Protein per pound of body weight (eggs, chicken, beef, fish, turkey, whey powder, Greek yogurt)
Minimum of 1.5 grams of carbs per pound of body weight (oats, yams, rice, fruit, potatoes)
Shoot for 20-30 percent of your macros as clean healthy fats (egg yokes, natural peanut butter/almond butter, olive oil, almonds, avocados, etc)
Most people who ask these questions have no clue how to eat, and want a quick fix. Everybody has to eat to gain, and someone like yourself that is a hard gainer needs to eat more to see the benefits. Even the pros that use a lot of gear eat tons of food to put on mass. Your way too small not to have great gains from simple supplements and healthy foods. You also may need to look at your workout routine. Stay away from cardio if you are looking to bulk. Lift heavy and hit every body part.