I know exactly where you're coming from. I'm 18 and I've been dealing with the same thing for as long as I can remember. I experience a lot of your symptoms, and I have a lot of panic attacks, as well. It seems like it's gotten a lot worse in the past year: now I don't even have to see a spider in the room. It's just the idea that there might be one there. When it gets really bad, I have to keep running my hands over my body to make sure there's nothing there, and I'm afraid to breathe incase I inhale any. That last one worries me a lot.
I think you should see the psychotherapist. I really want to; my college psych teacher referred me to a place, and I keep the number handy. The only thing is that my family doesn't understand. I'm sure you know how other people react to your phobia. If I were to walk into a room full of people and say that I have arachnophobia, half of them would say, "Yeah, me too, their gross!" and half would just laugh. That first half of people get on my nerves because not liking spiders is different from the disorder. People generally don't understand, and neither does my family. My parents have gotten really mad at me in the past when I couldn't clean the basement or the pool because of the spiders. So I really want to get help, too, but since I'm still financially dependant on my parents, I can't go.
It feels so nice to find someone who knows how I feel every day!