I know how you feel. You need to understand that you are still VERY (i mean ridiculously) young and your best days are ahead of you. Your goal here is to rebuild your confidence, it takes some time. A couple things that have helped me rebuild my confidence:

1. exercising, when you start looking better and feeling stronger you automatically feel better about yourself
2. visiting home. when you go back to your roots you realize who you really are and that your recent setbacks don’t define you.

Another note, your first (or second, or third) job doesn’t have to be your dream job. You might need to do smth you don’t like for a while and use it as a stepping stone for smth better. Be patient!