I'm sorry to hear you're going through so many stressful and unfortunate events.
I think it's possible your life can turn around but it might be in small increments you may not notice at first. For example, the Zoloft could become more effective with relieving your depressive symptoms. As you start to feel better, the people around you like your therapist and your family may notice your voice and behavior become more lively and responsive. You might gradually feel more resilient and less despairing over your future and place in society.
Do you feel your therapist is helpful at all? I think it can be so hard to be hopeful about your future or life in general when bad circumstances are dominating your life and it feels so impossible for things to change for the better. Something I like when I talk with my therapist is hearing a different perspective on what's been bothering me and how I perceive myself.
What dosage of Zoloft are you taking? I spent about 14 months on Zoloft and I went up to the maximum dose of 200 mg along with taking 20 mg of Buspar and 150 mg of Wellbutrin. I think the Zoloft helped with getting me to be more proactive with my life which in turned helped to improve my overall mood and outlook, but there came a time when I decided to switch to a different med. I'm not sure if it was side-effects or the Zoloft stopped working, but I eventually switched to a different med because of the tiredness and emotional flatness I was experiencing while taking 200 mg of Zoloft.
I lost my father unexpectedly when I was 23. Something that helped me with grieving his death was talking to other people about what I was feeling and how they coped with the death of a loved one. I'm normally a very private person so this was a big change in behavior for me.
I hope writing about what you're going through has helped you feel a little better and not so alienated.