I agree with what Gr3tta and Sometimes suggested. I also think you are doing a good job. Reassuring her during these times and pointing out she will be able to push through an "attack" is best. Remind her that she has had these attacks before, and that they pass. That is what I tell myself when I am terrified with panic/anxiety. I remind myself that it will pass shortly, and that I've gotten through them before.

I do not believe in calling 911. It is a very extreme thing to do, many of us here have experienced that when it wasn't necessary at all. I think our loved ones panic and they call 911 because of their own fears and insecurities. Having strangers like the police barge into what is supposed to be a safe sanctuary--her home-- can really only reinforce her feelings of suspiciousness and paranoia. Of course, if you or your daughter is in danger that is a different story.

I hope things get better and that you continue to reach out for help and support.