Bababel gave you some very sound advice, in every respect. I see a psychiatrist, and she is in charge of all my mental health treatment, including my anti-depressant region. As Bababel and I both mentioned, anti-depressants encourage the growth of new brain cells in the hippocampus region of the brain. I discussed this recently with my psychiatrist, and she told me that most physicians are not aware of this. Unlike most medications in which a person's weight matters, it is just the opposite with anti-depressants, like Bababel mentioned. You need to be on a therapeutic dose of Zoloft for it to work, and that lowest dose is 50 mg. If your doctor is reluctant to increase your dose, I would be seeking a second opinion (I suggest a psychiatrist.). And the standard is to be on an anti-depressant for at least a year, before there is any consideration from going off one.
I'm hopeful this information helps you to regain a normal lifestyle, in time.
The very best to you, Ssgirl!... Chuck