You are most certainly not alone in your situation. I receive many letters from teens like yourself who are carrying a burden that is too big but who feel like there is something wrong with them that they can’t handle. There is nothing wrong with them — or with you. Adolescence is a confusing time for most teens. Your body is changing. Peer relationships are often unstable. Additional layers of worries about family members or feelings of depression or anxiety can make it even more difficult.
Your letter shows that you are a sensitive person with big feelings who doesn’t want to burden others. Unfortunately, this leaves you carrying the burden on your own.
One of the advantages of therapy is that it is outside your usual relationships. A therapist’s job is to listen to you and to help you. There is no need to be embarrassed by what you are feeling. A therapist doesn’t judge and will not be burdened by whatever you have to say. Further, your therapist may be able to help you figure out how to both take care of yourself and also provide some support for your mother.
You don’t need to get over your feelings of embarrassment to start therapy. In fact, talking about that embarrassment may be exactly where you need to begin your first session. That will give you a place to start unloading some of your stress and will give the therapist the opportunity to reassure you. That is the beginning of establishing the trust you will need to have to do your emotional work.
I wish you well.