50 mg of Sertraline (Zoloft) is the lowest therapeutic dose of this selective serotonin reuptake inhibitor (SSRI) anti-depressant. Are you feeling any improvement at all?
Anti-depressants normally take 3-12 weeks to work, and will show ongoing degrees of improvement during this time, and beyond, so it is still somewhat early in your treatment.
I was started on Celexa some 4-5 months ago, and didn't really see a change in my anxiety until around week #10.
Anti-depressants are an interesting classification of drugs, and what works for you, might not work for me, and vise-versa.
Certainly I would encourage you to talk to your doctor at this point, about your concerns as to how the Sertraline is working for you.
The very best to you, Sarah!... Chuck