Hey Sara. I really think it's awesome you found the courage to go and get your diagnosis and start councelling, I'm not even there yet.
I think all you can do is try and hold on until you can get to that appointment and they can give you some methods on how to control your anxiety. When people say 'it's all in your head', they're quite right, but not the way they think. It's like a cognitive disorder but not one that you can just control, no. But at least it means you might be able to learn how to suppress it to some extent, and soon!
You aren't as lost as you think you are, you've taken a really important step and gotten yourself help and despite hitting rock bottom several times you still keep trying and finding out how to manage it all. I think that's pretty awesome. You still find strength even after losing your friends and I know how tough that can be. I really hope this forum can help quell some of your loneliness, because there are people here who can at least understand what you're going through and how it feels to be completely overwhelmed by your emotions. Just hang in there! I think you've gotten really far already, you just need to take a few more steps. Hopefully one day you'll be strong enough for a steady walk.