I have made my response too long. I am very nervous, too much anxiety every day. My doctor thinks if I go out and am more social it will help me be calmer when I am alone. On my own I am not improving so I think I must take her advice.
I'm interested in this part of what you said, because along with the way you describe being out and mixing with other people, I find it hard to understand how following your doctor's advice will help you with an objective of 'being calmer when you're alone'.
I understand that your reaction to people may be different from mine, but for me, being forced (whether by someone else or myself) into social situations would create the kind of stress that being at home, isolated and alone, would still take an age to come down from.
even if your sensitivity to public spaces and people could be reduced by exposure, which is certainly possible for some, though probably not for all, it would take some time to accomplish.
Given your wish to be calmer when alone, I'd be inclined to think about activities you could engage in which are more relaxing and which help you de-stress, rather than forcing something stressful on yourself.
As I see it, home, on my own, is my sanctuary. It's where I know I can go and be safe and unwind, so in your situation, I would look to build on that strength, not try and build on a weakness.
In your shoes, therefore, if it were me, I'd look at what makes me feel most comfortable and under control. I'd stay home, put a stack of books to read on the coffee table, turn on a favorite radio station, and settle down to read for a few hours in the evening or over the weekend. Once that has de-stressed me so I feel like I can breathe and feel comfortable, I might then go out and see how I managed in and around others, knowing I could always hurry home, pick up a book and turn on the radio to help come down again if it didn't go so well.
I'd suggest you find your equivalent of being home alone with a book and a good radio station, and build on the comfort that can give you.