First off, it's nothing to be ashamed of. Basically a panic attack is your brain triggering your "fight or flight" reflex inappropriately. Your body is preparing to either fight off attackers or flee from them, pumping adrenaline into your blooRABtream for extra energy. Unfortunately, without an enemy or disaster to fight/flee from, you're left feeling like you're having a heart attack or something. Blood work and all that - if it comes back normal just confirms that there's nothing wrong with you physically. Panic attack is physiological, meaning part psychological, part physical. The physical part is the nurabness, chest tightening, shallow breathing, etc.
I used to get panic attacks everytime I left the house, and would hyperventilate. Once I realized that I wasn't really dying, I learned to just pull over & wait for it to pass. Eventually I stopped having them. Antidepressants help tho - because I seem to have a permanent problem with seratonin levels in my brain, which is what anti-d's, at least the ones I've taken, affect. Klonopin is good to get you through a panic attack or stressful situation in which you are worried about having a panic attack, but the anti-d is what hopefully will straighten out your brain chemistry & help you get back to normal.
There are many techniques you can use to fight off panic attacks, and/or help you get through them. One is regulating your "self-talk". When you're in a situation where you have had panic attacks in the past, like driving a car, you can basically talk yourself INTO a panic attack by that voice in your head saying "oh crap what if i have a panic attack, I could pass out, wreck the car, etc." Best thing to do is hijack that train of thought & replace it with "I'm fine, there's nothing wrong with me, I'm going to be OK" etc. Another technique involves abdominal breathing, which I can't really explain but you can look it up on the internet.
Main thing is to do what you said - not let this take over your life. Keep getting out there & driving - if you start to avoid driving due to panic attacks it'll only get worse, but if you keep doing what you're doing the anxiety will ease over time.