I totally agree with you that panic attacks are evil. I wouldn't wish them on my worst enemy!!
You're absolutely right that it can really make matters worse if we start worrying about when we're going to have the next panic attack. In fact, that is the definition of Panic Disorder. In other words when you get caught in a cycle of fearing the next panic attack, then you have Panic Disorder (my psychiatrist told me this and I have experienced it first hand!!).
It's really difficult to break the cycle of worrying about the next panic attack. But, one of the worst things you can do is to start avoiding places and situations (even though that is kind of the natural response!!). I have been down the road of avoiding things and it just leads to more problems (and more anxiety).
So I would really encourage you to continue doing your karate classes and to continue driving, and everything else, EVEN IF you are a bit worried about having another panic attack.
As for trying to figure out what triggers them, that's the other definition of Panic Disoorder: it's when the panic attacks happen out of the blue and not in a specific situation. In other words, you may not be able to figure out what's causing the attacks. I have had some of the worst panic attacks in my own bed, which is really not a scary place, and yet, for whatever reason, that's where I've had some really bad panic attacks.
It can be really helpful to work with a therapist. For a lot of people, anxiety issues respond well to therapy, especially Cognitive Behavioral Therapy (CBT). So I hope that might be an option for you?
I have also found it helpful to learn as much as I can about panic attacks and Panic Disorder (there is a ton of info online and there are some good books on it also).
Well, I didn't mean to write such a long post! Just want you to know that you are most definitely not alone with this!! Let us know how you're doing!!