This is an important question and should be asked to those who treat children, which is the child behavior forum on this site..
medhelp.org.
In general, the low doses are best and give maximum benefit while the high doses don't add much, but do add side effects.
Zoloft is known to make people feel agitated, and that is what your daughter may be describing, so paradoxically, you might talk to your doctor about lowering the dose and see what happens.
She should be getting talk therapy as well as medications for this...and I do not know the long term effects, so you should search this out diligently.