Hello Aqua and welcome to the site. I don't know if you have ever tried CBT before. I would like to assure you that CBT is one of the best therapies for anxiety/stress, OCD. I hope you begin the program soon and stick with it. There is no race to finish any one chapter, do at your own speed and even go over something as many times as needed. I have done this program at least 3 times and am panic free. I recommend the relaxation exercises and breathing techniques you will learn. Practice these faithfully, every morning and night. When you have an attack, or feel one coming on, these techniques can really help calm the body and avert an attack. They will also help you with going outside again.
My suggestion to you right now is to just sit outside your house, on the front steps, the back yard, wherever you feel comfortable at this time. Bring a cup of tea/coffee with you and sip slowly. You only have to remain outside for 10-15 minutes every day. This is the beginning of what is called exposure to your fear - in your case fear of going outside. After you have done this for awhile, walk around your yard every day, enjoy the scenery, have your cup of tea/coffee, then go inside. All of this is explained in the CBT program. Having coping techniques such as the relaxation and breathing will help you through anxious spots.
To give you an example, I knew a lady who couldn't walk out past her driveway. The sidewalk frightened her - couldn't even walk on it because she thought she would trip and fall, freak out, etc. She started by going on two or three squares every day in front of her house. She kept adding a square or two every so often. By the end of the month or so, she could walk right across a very busy street! No kidding.
Keep a positive attitude, and believe - CBT is about turning negative thoughts to positive ones. What if's become, so what, I'm doing it anyway because I choose to do so.
Good luck.
Sunny