I'm glad you have found your way here....welcome! There are wonderful people here who know the pain you are experiencing.
It's great that you realize that these are not your concerns to own; they are your mom's. Knowing it and being able to live it are too different things of course, but coming to that understanding is a very big step for you. I also tried to do everything I could for my daughter to "help" her until coming here and going to Naranon meetings helped me to understand that I wasn't helping and could be hurting. I needed to get out of the way and let her find her own recovery. I also learned through trial and error that worry and projecting into the future did nothing but make me sicker. It's so difficult not to, but with trust in a higher power, it helped me to let go of what I was powerless to control.
I hope you will stick around for you...it really helps. Hugs and prayers.