It's been many years since I went through what you're talking about, but I just had to respond.
My panic attacks started in high school. One day I had one during a class, and I got up on the premise of taking a washroom break. I never returned to school after that day. The rest was pretty much a spiral into severe panic and depression. My parents didn't understand what the hell was wrong with me. I got all the "Snap out of it" speeches and what not. The thing is that this is a REAL disorder, and what you're going through deserves serious respect and consideration. If you could just snap out of it, you would have right? It's like they think we enjoy the terror that panic wreaks on our lives.
That being said, I think you need to understand where they're coming from. They don't know anything about this disorder, and they're probably afraid to face and acknowledge that this could be a real problem. Your focus should be on "You", and making yourself feel well. I know it's hard to ignore the criticism of others, but I've learned through the years that they are mostly ignorant of just how deep this goes, and what it really is.
Anyway, that's my 2 cents for what it's worth. Good luck to you, and don't feel guilty for having this problem. There's MANY like us out here. *S*