I think it sounds like you have it a lot worse than me, so apologies if I just regurgitate things you've already tried. And I hope you're feeling a little better this week!
The biggest proactive things for me in preventing attacks were kinda holistic. I tend to think of migraine like a forest fire, and the preventative stuff akin to forestry management.
Being really strict in life routine to avoid the body being any more stressed than needed (so, bed before 11, no screens after 10, food at 7, no snacks after 8, lots of water drinking) had the biggest impact.
It meant that when I did get an attack, there was more "slack" to deal with it, rather than it becoming a spiral each time.
Diet wise, cutting out a lot of processed fat/sugar, and reducing the amount of salt made a big difference too. Caffeine is a double edged sword for me, if you do currently use it, cutting down can help a lot.
And in the summer particularly, keeping tabs on exertion. I hate paying for taxis, but if I'm 3 miles from home and I'm getting the precursors to a migraine, I'd rather lose a tenner than get walk back and spend the evening screaming.
You're probably a lot more experienced in reactive action for migraines, and probably in another universe than me if you experience multi-day.
For me combining breathing exercises, meditation, and paracetamol helps enormously when trying to "dampen down" an attack, to use the forest fire metaphor again. I found that getting myself calmer had a positive feedback effect, and combining that with nsaid painkillers helped de-escalate things.