Generalized anxiety means exactly that: The anxiety is generally there much of the time about many, many things. However, I can’t tell whether you have the normal anxieties of every person who is emerging into adulthood or whether you have a “disorder.” It’s important to make the distinction. What you need to do to help yourself depends on accurately understanding the problem.
Many many teens have the anxieties and concerns you listed. Many many teens are easily embarrassed (especially by family members), are uneasy socially and very concerned about how to fit in. If your worries are within the range of normal, the “treatment” is to watch and learn from others, to take your time when you are nervous, and to remember that this is all the sometimes uncomfortable part of growing up.
A disorder is more pervasive. People with GAD (Generalized Anxiety Disorder) worry excessively a good deal of the time. It interferes with their functioning in their schoolwork, jobs, and relationships. They are often irritable and depressed and sometimes are even suicidal. There are often physical symptoms as well, such as nausea, diarrhea or irritable bowel syndrome, headaches, sweating, maybe sleep disturbance.
If that is the case with you, you should see a professional mental health counselor for an evaluation. If diagnosed with GAD, treatment will include talk therapy to teach you skills for managing your anxiety and for becoming more self-confident. Sometimes a medication is also recommended.
I wish you well.