In regards to regulating your breathing, that's a good approach. I don't know if this is helpful to you or to anyone else here, but I struggle with the whole counting how many seconds to breathe in and how many to breathe out, so what I've often done is combine regulating my breathing with a sort of mantra; I breathe in while thinking the words 'breathe in' fairly slowly in my mind, and then hold that for just a moment before breathing out while thinking 'and breathe out, everything will be fine'. The longer second sentence helps make sure my exhale is longer, which I've heard is calming, and it also has the benefit of being some reassurance to myself, no matter how small that reassurance may seem at the time. I've mostly ended up using this technique when I can't sleep due to anxiety, but it's useful in general as well.