Please help! I don't know what to do?

I am 17 years old and a female. I had a bad past and I am not getting into any of that. But to make a long story short, I ended up in a hospital, more then once for cutting and eating disorders, and multiple anxiety disorders and depression.And my whole life I was highly sensitive and I always took in, not only what was going on within myself, but everyone around me, and I was always like my mothers mother, but I am not getting into that. But because of the hospital and all this stuff going on, I had to be left back in school, and it's kind of like a new start for me, because I went to go live with my grandma and a whole new school, which I am enjoying. But then I fell into the trap again of taking on every ones problems, and today I just started crying hysterically because as much as I want to help people and be there for them, I really need to focus on my school work, art work, and myself, and if i don't, nothing will amount to anything. I feel so guilty though everyday, because I need to be there for certain people, but I don't have the time and I realized if I don't start doing any of that now, I will never, get into the college I want to, and I will never to be able to help all the children and families I want to(I want to be a social worker, and specialize in expressive therapies.) My question is, is it worth focusing on myself now, for all the things to happen for the future? but I feel so guilty, because those people need me, but I just don't have the time to go out of the way to do it or go out of my way to volunteer, like I wanted to, especially this year. I have SATS and HESPAs, and all these clubs, and my artwork, and for once in my life I have friends and a social life. Should I feel guilty, or just focus on my work and rebuilding myself and my life? I don't know what to do.