I haven't posted here in a quite a while myself! I guess thats the trend of the week. Anyway, for better or worse I have some personal experience of your problem. I am surprised that zoloft was prescribed as its intended to treat depression, and there are drugs, (Buspar for one) that are specifically for anxiety. If you aren't seeing an actual psychiatrist, maybe it would be a good idea to do so. (You're a therapist aren't you? So you probably know that already.)
I'm currently on buspar and am weening myself off of zoloft because I told my doctor that I'm ready to try to get off of both of them. Its been 3 years now. Anyway, I recommend you look into buspar and other anti-anxiety drugs. Also XANAX. I've taken just a few in the year since it was prescribed, but I carried them with me everywhere for about 6 months like a pharmaceutical security blanket! They are a valium relative I think. I take them if I'm having a panic attack and they totally bring me out of it. Its really useful that way.
You may be extremely sensitive (like I am) to all of these type drugs and should talk to your doc about starting slow. For instance, I only take 12.5mg of zoloft per day which is half of the smallest pill they make and I had to start by taking it every other evening. If I took it in the morning it messed up my stomach and I wouldn't be able to leave the bathroom, but my psychiatrist told me to try the evening and it helped for some reason. The buspar also, I'm on a geriatric dose according to what I read online. (I'm in my 30's)
I hope some of this is helpful. Its an awful thing to go through and even though so many people experience it it seems as taboo as ibs or even more, to talk about it. (did you read about Penelepe Cruz ahving a panic attack on an airplane this week?)
There are books too of course. Just type panic attacks into amazon and you'll find lots of books and lots of reviews. I used one of them and wrote myself some notes that I force myself to read when having an attack. It can help a little, especially if I catch myself early.
Hang in there.
Ladies & gentlemen take my advice, pull down your pants and slide on the ice.