Grasping at straws

Hi im Darci. I've suffered from severe social anxiety since childhood and depression since i was a teen. Im in my 50s now. Mental illness has defined my life. I've tried so many medications and therapists, and some things have worked for a while - giving me the ability to go through the motions and function day to day - but it seems in the end the depression finds a way to return. And its these times that I also get angry at how unfair life is, that some of us are born into this struggle. My anxiety and horror at the thought of truly letting anyone in, has robbed me of any meaningful relationships in my life, even with my family. Maybe because of that, my life has no meaning or purpose. When I am doing well, I am still just going through the motions of a life. When I was younger, i had this vague hope that someday I would find the answer. But now in my 50s i feel like im close to the end and my whole life has been nothing but a wasted struggle. And its not fair. How is it that others seem to find happiness and fulfillment? I'm so afraid that I never will.