Pursed lip breathing is fairly cut and dry. You inhale through your nose for a set amount of seconds. I use 4 second inhales. Then you exhale through your lips when they are pursed for twice as long. Pursed as being like when you blow out birthday candles or going to kiss someone on the cheek. If your inhale is for 4 seconds, your exhale should be 8 seconds. This is my understanding as to how to do it properly. This does not mean that there isn't another way to do it, it is just the way I was taught through pulmonary rehab. , if it definitely helps you recover when gasping for air, then I would say you are doing it correctly. Take care and God Bless!