I'd also not dare to recommend that you take any psyches. But I would like to chip in if your going that way.
There was a poll on here a while ago that resulted in cactus/mescaline being voted the least likely to cause bad trips, so if you insist on trying a psychedelic, I'd suggest that. Start with a mere 3-5g of dried torch or pedro, depending on potency. You'll get a psychedelic mindchange with a nice mdma-ish glow but not much in the way of visions. Even at this level it's possible to have negative emotions (dreamer has experienced sad, lonely, unhappy, yearning, sympathy, but never panic nor anxiety... and it's usually positive emotions) so be mindful of set and setting.
However, learning to let loose of control is one of the biggest lessons of ayawaska (and DMT)... I'd never dare suggest it, but who knows, for a person without your issue I'd say that is one of the major benefits (people are such control freaks), so I can understand you being interested. I have to admit if I were having panic attacks I'd be tempted to try ayawaska to see if it would shamanically cure me (it cured a dreamer of his mild CFS/ME or depression, so he has an almost religious faith in its powers to cure the human brain), but please don't take that as me thinking you should try that. If you do decide to go that route, maybe start with ayawaska alone? Say, a 25g brew? (What do others think?) Then if that's ok you could go higher if you wanted (50), or start introducing DMT admixture plants starting at a minimal dose then working up slowly each session until you find your visionary dosage level.
One things for sure, smoking DMT is I'll wager a definite no-no if you have panic attack issues. Panic was one of the mainstays of every launch for that dreamer. After launch it calms down, but I'd be concerned that that could trigger off one of your attacks (not that I know if it would or not).
By THC, you mean the stuff in skunk weed? That stuff can indeed cause panic.
Most importantly, you have to ask yourself: are you willing to risk setting off your panic attacks again with these experiments? I mean, it's an imaginable possibility. If the answer is no, then maybe you want to play safe and just enjoy the consciousness you have now. Only you can weigh up the pros and cons, it's your life to explore as you wish.
Good luck in whatever you decide. And yes, life is indeed a trip, I think that a lot! 