Op I feel for you, I've been there.
When my anxiety was that high I noticed that what I ate had a direct impact, if I ate rubbish or little the night before, my heart palpitations and panic attacks would be worse the next day. So, I'd maybe pay closer attention to see if there's more of a correlation than you've noticed.
Classical music also helped and im not usually a fan!
You could YouTube Kirtan meditations, they're good if you struggle to get into the zone for meditating.
As its your own business, is it possible you could book a few days away in a different county under the guise of business needs?
( I expect to get flamed for this, but if your mh is hanging by a thread and don't come into contact with other ppl, I think you'll be ok). Just somewhere different where you can blow the cobwebs away- i did it after lockdown #1 last year and it made a massive difference to me.
I'd also approach your gp and see if there are other medication options that might help. If freelancers aren't helping atm it sounds like you need something to help you through until things can ease up a bit.
Perhaps there are better ways to manage your clients - when we're in the middle of the storm and so stressed it can be difficult to see the wood for trees so maybe a business consultant might be able to help you?
If you're not getting on with yoga, try other gentle exercises...maybe pilates, tai chi or ballet? If you enjoy dance, any online dance class could help.
How about a punch bag for taking out your frustrations at the end of the day?
You might also like to consider talking therapies, many local authorities allow you to self refer and its free.
Picking up a new hobby can help, something you can do with your hands gives an outlet for the built up anxious-energy and the focus can be really soothing.
Audiobook etc. Carve out time daily for self care and go right back to basics if you need to. 