Samanthia.
This reminds me of problems that some people suffer from in various guises. The solution is surprisingly easy and successful.
You start by imagining yourself in the various situations which are causing anxiety. In your case, walking outside.
Next, you add into that, in your imagination, your worst nightmare, it could be someone specific, seeing you, it could be gtting arrsted, it could be, being attacked, whatever it is, you need to add that image into your daydream.
Now, you deal with it in your controled environment. It is controlled because you are in control. Total control.
Now try this. It isn't going to work instantly. To start, you're probably going to find it very difficult to concentrate. That's what most people find. That's just your fears, taking control. You are doing this to eliminate these fears so start by taking control of them in your own environment.
Good luck.