Something I'd suggest would be touching your fingers to your thumb. I do that to myself all the time. Or like pressing my thumb to my palm and circling it. It kinda grounds me and helps me breathe with it as well, and it's easy to hide in your pockets or under a desk :)

I struggle witht this alot and completely understand what you described, anxiety & dissociation van be the worst Personally, when i start to get overwhelmed or can feel myself drawing back (which is quite frequent), i 1st just try to relax my body and mind, and try to breathe. But thats for smaller attacks. When it comes to dissociation, i try to identify something relating to all the senses, it grounds me a bit more. But heres a few other things i recommend: 1: try eating if possible, it gives your mind something to focus on and sometimes hunger can mess with your emotions even more 2: this breathing technique i use is counting as long as you need on each breath in and out (ex: you breathe in a say 1 to yourself, breathe out and say 2 etc.) Hope these help, you're not alone, and if you ever need to talk im open 💕

Personally, I use carnelian combined with pyrite. That may be tied too much to spirituality, but it works for me. It doesn't always work but it's worth the try.