Hi Maddferit,
I'm 18 too, and have had panic attacks since I was 15 but my agoraphobia/avoidance goes back further than that. I've had quite a few times where my anxiety has been severe, for six months or more at a time. It is such a long battle, but I know you can do it!
There is no way you can rush this, and if you try it will only make the anxiety worse. I know what you mean about not feeling the same. I can't even remember the person I used to be, the things I enjoy or how the old me would react to things. The one thing I have learnt that has helped the most is to think of your anxiety as a separate part of you. The further away you can distance yourself from the anxiety, the more you can fight back and challenge it, the more your 'true self' will show through and you'll start to feel like yourself again. I hope this makes sense.
You're not insane. How would you picture someone who was insane? Would they be totally distanced from reality, in a padded cell babbling to themselves? Even then, to call them 'insane' would be harsh. You're also not pathetic. Just because you think something, doesn't mean it's true.
You haven't been bugging anyone, it's good to post on here. I find it helps put things in perspective :)
All the best,
Kaitie.