I started having anxiety problems when my first child was about a year old, and it got much worse recently during my 2nd pregnancy. I started taking zoloft when I was about 30 weeks along, actually my OB prescribed it! She wants me to wean off of it before I deliver, but I'm not sure how that will go.
I'm also seeing a therapist, and that helps me find ways to deal with the anxiety. A big part of it for me is spending more time working on things I can control, and less time fretting about things I can't change. For example, I had a really bad experience with my first labor & delivery, so this time I switched to a different OB, and we hired a doula who has done some classes with us and will be there when I'm in labor.
The zoloft didn't really change my personality, but I feel like it gave me a huge attitude adjustment. When I feel a panic attack coming on, I'm able to think more clearly and find a way to calm down.
If you can narrow down the things that are bothering you, it's unbelievable how much it can help to do something productive. When I start to worry about not being ready for the baby, it helps a ton if I go organize the nursery or pack the diaper bag, something to help me focus and feel more ready!