I'm sorry to read that, but look on the bright side you're better than you were.
"I worry about everything, and it's been incredibly difficult to find a way to let it go."
That's the key isn't it, letting go. I think it's different for everybody, but for some reason your mind won't let you relax. For some reason your insecurities need to be fed. The reason might not matter. Maybe it would help find a solution or a way to deal with it, but you probably already know.
When I was young I was a worrier, fearful and scared. I don't know why. When I was very young I stuttered and my mom helped me get over it by having me take a deep breath, slow down and relax. That was the key. Take the pressure off the first syllable and let it out. The rest will follow.
When I was a little older I asked myself, what was the worst that could happen? Chances are, that won't happen so what am I so worried about? I'd go through my worst case scenario and anything less seemed easier to take. Most of the time nothing happened or maybe I was praised for doing a good job.
I always knew that worry was counterproductive and made things worse. Panic is an extreme response that blocks rational and creative thought. You want to run and hide.
Life is a terrifying thing, full of imaginary monsters and ghosts, not to mention the real pitfalls. The realization that we're all alone is scary. Everyone is all alone, they might not realize it, but they are. Some people have a spouse or partner. They're alone too, but have to spend time catering to someone else. More worries?
Visualization helped me immensely. See yourself in a good place and figure out ways to make it happen. Think of how things can be better and plan for it. At the beginning of a trip visualize a parking space where you're going and keep it in the back of your mind. See if it works. Watch a funny movie and have fun. Somehow you have to trick yourself into letting go. Whatever works.
Regards,