how to know if shortness of breath is dangerous?

for months, ive been having shortness of breath that comes and goes. This time, its worse than any other time. i feel like im choking, and i even wake up out of my sleep feeling like i cant breathe. i had two echos, three ekgs, and xray of chest and blood work in february that came back normal. i am going to cardiologist in a couple of weeks for my yearly checkup, and im super scared.

dont be scared. the tests would have shown a problem when you first had them. shortness of breath is a scary anxiety symptom which many people on this forum have had or are currently suffering with. it drives some people crazy always thinking they cant get a nice deep lung full of fresh air.
does this only happen you wake up or through out the day.?

both, but it comes and goes. if i can get my mind off of it, it seems to go away

trust in the testing that you had done. They came back normal. Anxiety can make you think you have something horrible. There are some great breathing meditations on YouTube that get you in control! That is what really helped me. Breathing is the key to managing anxiety. There is one called mindfulness breathing guided meditation 10 minutes. It’s important to know the proper technique and it also helps you get control of your thoughts. Another one I really like is called stop panic attacks now!
even if you’re not having a panic attack this is extremely great in calming you down. and slowing down your breathing.

by the way, shortness of breath caused by anxiety is never dangerous. It may feel like it is but it just caused by adrenaline that is released during anxiety.