Worth is determined by how you value something and Self-worth is determined by the extent to which you deem yourself excellent or lacking and how you value yourself.
How do you see yourself? You are, to some extent, living an in-authentic life. You have created an image, a created self to fit in, to be accepted and to be loved. Everything you think, say and do is caught up in your quest to be valued by others. So your self-worth is being determined by an outside person or group of people who have never been able to see the authentic you.