I've been on 50mgs of Zoloft since Sept 2012, and about a week ago I upped to 75mgs.
I still have/had break through attacks even at 50mgs, I only increased because of certain life stressors that were causing me to get very stressed, which kick started my attacks.
Zoloft is only a daily management med, it's not a miracle pill that's going to stop the attacks on it's own, you have to help yourself too. If you feel an attack coming on, the Zoloft should help keep you calm enough to get through it using whatever skills work for you. If you're really struggling though I'd talk to you Dr, maybe Zoloft isn't the right med for you?
I also have Klonopin I can take as needed for break through attacks (depending on how bad they are)
At 9 days of an increase your body is just starting to feel the effects of the 100mgs, one of the side effects I hear quite a lot about is increased anxiety for a bit while you increase your dose until your body evens out