Agoraphobia with panic disorder medication help please?

I had to stop taking Mirtazapine last night as the side-effects I was getting from it are apparently rare and will not go away. I have already taken Citalopram, Sertraline and Mirtazapine for my anxiety but didn't get on with them. I have a phone appointment with my GP this evening and would feel better knowing I had an idea what medication might work best for me. I don't want to take Prozac or anything that will make sick/vomit, dizzy or mimic other anxiety symptoms. I need something that is suitable for long-term consumption. I am receiving CBT by a psychotherapist but really need the added support of a good medication. I've done a lot of research on the available anti-anxiety medications but can't find anything myself that looks suitable. I have had a panic disorder with agoraphobia for over 4 years now and am twenty years old. I don't drink alcohol but I do smoke (about 10 cigarettes a day). As I have already mentioned I will speaking to my GP today, as good as he is I don't think he puts much effort into finding the right medication for me so I thought a suggestion from an anxiety expert would be a great help for me. Thank you in advance.