Your letter shows yourself to be a sensitive, caring young man. I very much appreciate your desire not to stress your mom. However, what you may not understand is that it will be far more stressful to your mom to find out later just how much you have been struggling.
You asked how you can fix yourself. Although I understand why, I hope you will consider this: Sometimes everyone needs some outside help — if only to get the information needed to then do the self-fixing.
The problems you outlined are real and deserve attention from someone who can get to know you in all your uniqueness. Please talk to your school counselor about how to get an appointment with a mental health counselor. In many places there are free or low cost options for teens. Then bring your letter to the first appointment. That will help you jump start the conversation.
You made an important first step in writing to us here at PsychCentral. Please take care of yourself and take the next step by making that appointment. We care.
I wish you well.