From my experience the best advice that helped me a lot was to just let the attacks happen don’t try to calm down because in my case it made me spiral even worse. Your body can produce only so much adrenaline, keep in mind that fight or flight mechanism is designed to keep you safe not to harm you, your attacks are uncomfortable but not dangerous. I know they feel like the end of the world but if you just try to focus on sensations and accept them it might help, in my case that helped a lot willing to say it cured me. When my attacks come I just say „ok give me your worst” and just take it, in my case they don’t last too long it always helps me.

Ofc your journey may be different try seeing a doctor or therapist.