You've laid out all of the puzzle pieces right there, in perfect order! All you need to do is put them together
You say you're fine at work, when busy and around people
You know that we can overcome anxiety when we "need" too.
You are bad when you're at home with down-time.
*And anxiety meds have made it worse in the past, plus you don't want to be on them.
What I suggest, and I have a big long section in my book on it, is that you make a schedule.
You DON'T need to be working all day and night through following a schedule, and you can even schedule plenty of things for relaxation, fun and enjoyment.
This is what I personally would do, and it may be of help to you.
Get a piece of paper and pen and write out all the things you NEED to do in a day, and what times you need to do them.
(Wake up, eat, go to work, come home, shower etc etc etc.) Be thorough with it.
Where you see gaps of time, fill these gaps in with something: Watching TV, go on a walk, cook, read, socialize (whatever you would like. But try get yourself doing things that you know will occupy yourself enough to stop the anxiety.)
When you've got a schedule ready, follow it as best as you can each day, and see how that goes.
If your schedule is too hard and rigorous, simply take out a few things and replace them with easier to do activities/chores, such as instead of going on a 8 mile walk each day, go on a 30minute walk and use the remaining time to stretch or have a snack etc.
I personally found that when I was occupied throughout the day, even facing my fears when I was facing them, that anxiety simply didn't have enough room to occupy my mind!
It's impossible to think of two things at the same time, or feel 2 (opposite) emotions at the same time. (* try picturing the statue of liberty and then in detail remember what you ate last night for dinner) You'll find you can only go between the two (even if it is fast enough to seem like their the same time) but you can never truly think of both...Well if you can, you're a super savant and I envy you
It sounds to me like this could help you. Let me know if you need ideas to fill your downtime with.
I have a massive list of things I do and did