Being strong for your mother would mean that you might be acting all grown up whereas you are still a teenager. This itself presents a challenge for you, where your needs might go unmet. Not having a dependable parent figure in life can be scary and traumatic. I suggest that you see a counselling psychologist for an evaluation and further course of action in your city.
Health Tips
Keep your friendships going. It will act as a stress buster. Go out of your house and indulge in your hobbies and interests. Find a nurturing parent figure (role model) for yourself and take guidance from them.