Hello, im 16 weight around 135 pounds, don't worry about how you look my friend im as light as you. Don't worry to much what you eat foget the protein shake whatever as long as you eat properly breakfast, snack lunch, snack, dinner thats it, if you do some running cut it short. Building some body mass only work if you eat correctly with excercise, I found out I was gianing weight because I eat alot I was 128 Pouds. You can't gained 20kilos over a night work everythings takes time, I don't know how plenty water you drink, if you do exccercise eat alot to compensate it. Oh by the way your not 5.8 feet your 5'9'