Your "shakiness" is a very normal reaction to Zoloft (Sertraline). Zoloft is considered a very “nervous” drug, as it can sometimes make you sweaty, shaky and generally uncomfortable in your own skin, more so than the other anti-depressants in the selective serotonin reuptake inhibitor (SSRI) class.
The good thing is that this is normally a start-up side effect of the drug, and these symptoms usually diminish greatly in 2-3 weeks. Do be aware that if your doctor increases your dose of Zoloft, you might see a temporary return of the start-up side effects, but again, they should not last long.
Zoloft is an excellent anti-depressant, and I have a number of friends on this medication. For treating anxiety disorders, most people will require 100-150 mg. And I have one friend of mine who is on 200 mg, and doing well with that.
The very best to you, Zooey!... Chuck