One of the things that comes through in your letter is a desire to change. While I hear the frustration and sense of not being able to evolve past all this, I am also very much aware of the fact that you very seriously want a positive change in your life.
First let me say that you need to find a way to minimize the effect your mother has on you. If there is any safe way you can get away from such a toxic individual do it now. How can you get healthy and have peace in your life when your mother gives you exactly the wrong information? I would perhaps ask your grandparents for help directly. Your mother isn’t giving you good information. That is a sign of her own pathology, and not something for you to accept.
I am going to recommend the National Alliance on Mental Illness (NAMI) groups in your area. Here is a link to those. But you may also need a psychiatric evaluation so some medicine can be prescribed. I would make an appointment with a psychiatrist in your area as soon as possible. If your grandparents are not able to help, you can use a local clinic who can provide services for low or no cost. Use the NAMI site to get information in your area.
Here is a self-help site for dialectical-behavioral therapy (DBT). This is an effective form of therapy for some of the symptoms you have described, and you may be able to find a program in your area. I would also consider the PsychCentral forums here, which are free.
Use your desire for change to find the help that you need now. The symptoms you’ve described are difficult, but certainly possible to cope with.