I don't have advice about
the worthless feelings, but I can say that my body reacts very differently to those two medications. Ativan works pretty quickly for me and takes the edge off my anxiety; I've only ever taken it occasionally, as it sounds like you did. Clonazepam did absolutely nothing for me, that I can recall - no change in anxiety, no good feelings, but no bad ones - basically, it left me feeling like I hadn't taken anything. This was also on an as needed basis - well, if I needed something, I always took the Ativan after that.
I hope you're able to get in to see your doctor very soon - Good luck!
Co-Moderator, Anxiety and Panic Forum