Are you on any type of meds for this? If not, I would try deep breathing/ meditation. When you feel your anxiety about to rise, start breathing deeply. In through the nose, out the mouth. Nice slow breaths. Do about 20 deep breaths while keeping your eyes closed.
Pick a small item from your personal property (something that can fit in your pocket). Institute the idea (and believe it!) that when you are carrying this particular item, nothing bad can happen to you. When you are out and start to feel anxious, pull the item out of your pocket and rub it in your hand while taking deep breaths.
Agoraphobia is a recognized psychiatric disorder. It's real, and can affect your whole life. I didn't leave my home for 3 years, but I had a severe case. There are many anti-anxiety meds you can take. See a mental health provider. Try visiting this site. http://www.nimh.nih.gov/index.shtml