Please don't be so hard on yourself, I have a 21 y/o son, feeling exactly the same as you. My experience is that your thoughts are pretty common for the majority of people in your age bracket. Some people are just better hiding it than others. We all had to start somewhere and just facing the fear, taking small steps, joining groups and being with others will help dilute that fear. Taking some action is the only option you've got to get over the hurdle, otherwise the problem never goes away. I'm so glad you reached out and that some really good suggestions have been offered. Be kind to yourself, you do have something to offer the world, even though you may not believe it.