You need to eat big to get big... Increase your carbs and your protein... Bigger portions... And lift heavy weights.. Stick between the rep range 6-12... You have to sleep on a caloric surplus... If you do this you will get bigger..
To piggyback off this sound advice, you need to tax your central nervous system. If you're doing it natural you have to activate your endocrine system through lifting heavy compound multi joint exercises. Squats, dead lifts, lunges, bench press, cleans, jerks.... Back off the cardio and Eat eat eat! Good luck ectomorph your somatotype is a challenge!