You want to make sure you get at least 1.5 grams of protein per pound of bodyweight every day. In the beginning, everything hurt after training. It takes a few months for your body to adjust. Switch your training routine constantly so you shock your muscles otherwise you'll hit a plateau. Eat 6 meals a day and try to continually increase the amount of food you're eating.
Great work dude, but TBH you would have gained some mass in that time period even if you hadn't worked out......you were 16 when you started, you would have grown some anyway even without training. Still, good job, keep at it.