I am sorry you go through this. I used to have severe panic attacks. I had tried so many approaches, many of which are listed above. I had also needed medication to keep my anxiety level much lower.
I have not had a panic attack in years now. Medication stops them before they start.
Not everyone needs medication. Many different strategies can help and there are great examples/suggestions in this thread.
My pdoc has always stressed the importance of intervening in panic attacks, as they can become self-perpetuating.
If you hyperventilate, try breathing into a paper bag.
I hope you find relief!

WC