Hi s:) Use google for good (instead of symptom checking:) and search 'deep diaphragmatic breathing'. There will be many links.
Also maybe search 'breathing for anxiety relief', as well.
Learning how to breath correctly takes practice and patience. When we are amped, we have little patience, I understand. But, we are trying to introduce a new habit to our daily lives, so it will, likely, take some time before you can embrace it, fully. That's not to say that you can't start feeling some of the wonderful benefits of deep, belly breathing sooner than later. This type breathing helps with our whole CO2 / O2 body chemistry....it is science and physiology, so it WILL work if we keep up our practice:)
An anxious mind tends to amplify thoughts about stuff that we preceive as "off" going on in our bods. If you are analyzing your breathing, constantly, and feel you are not breathing correctly, then you will probably believe as though you are shallow breathing more than you actually are. It's tough to push through the intrusive thoughts, sometimes. The thoughts come in at lightning speed and we are left to work our way through them and it is our habits and actions that really matter when we get barraged by some intrusive thoughts. If our thoughts are something like, "OMG, why am I breathing like this...I feel like I'm not getting enough air in....I feel my chest is tight...Is something wrong?....Why can't I breath right?....I hope I don't pass out sometime soon!", then we can conscientiously try our deep breathing techniques and try to nip the panic in the bud. Through practice, good breathing can become very natural and it can become almost automatic in its response to an anxious moment.
The barrage of intrusive thoughts tend to lesson (I didn't say go away completely:) when we have begun to move down a healing path for our anxiety issues. It is part of our trials - the overanalyzing things going on in our bods. We, simply, have to accept this and work on embracing good habits and actions (and inturn mindsets). And, THEN, we have a good chance of learning how to live in better accord with our anxiety issues and have a better chance of not having our intrusive thoughts elicit dominant fear or hyper panic or drive us into counterproductive habits:)
Peace and Feel Well:)