I use Diazepam, have done for almost three years, sparingly. Or as sparingly as possible, but like you, take more than I'm meant when things are really bad. I have tried Propranolol before, it slows your heart rate down as far as I know, it's a beta blocker. It's not suitable for asthmatics, I have mild asthma but it didn't have any adverse effects and some doctors will prescribe it if its only mild asthma and hasn't caused you any real difficulties. It helped a little, but obviously not as good as Diazepam. But, because it slows things down, it can help combat panic. I've also tried Buspirone, but that never helped at all. It does some people but I personally didn't find it helpful. Have you asked your doctor about other meds?