you should understand the difference between depression and disappointment. disappointment also manifest symptoms as in the case of the depression. were you deeply disappointed in the near past say within one year? you did not have any bad experiences and your family does not have any depression history. that is perfect. you feel numb sad and worthless. feeling irritable and spending more time alone. these are some of depression symptoms but your problem is never depression. from the given symptoms i see this as an attitude problem related to some sort of disappointment. you are just 19. i suggest you forcefully change your habit. do not be alone. be with family members or friends. if you do not have friends then make friends. go outside and socialize. engage in physical activities and outdoor or indoor games. you will have many things to study. do it. divert your attention to more productive creative and positive things rather than brooding yourself worthlessly. i do not see depression now. if you continue the present attitude and behavior further then it could lead to depressive disorder. please do compulsively as i advised. for further information consult a psychiatrist online --><link>
how to confirm depression?