It may not be something you get over, it may be something you need to manage for the rest of your life. I am 22 now and I remember all the horrible feelings I had when I was your age. The doubts I had within myself. But I got through it, with the help of other people and with the help of myself, finding who I was as a person, what I liked to do, what makes me happy. I still struggle but I know I am in a much better position than I was back then mentally. It takes a lot of thinking but it also takes some personal reassurance that you will be okay. Outside resources are really important as well because sometimes we just don't know what we're on about. Especially at that age, you've got enough stressors externally, work, school, friendships and the like. You will get through this if you take your time I promise.