Not being able to breathe right is a very frightening thing. It is best to try and remain as calm as you can so that she does not feel your vibes.
I have lived with four CT pups...all varying degrees and it can be very scary at times.
Don't beat yourself ... you took her outside to enjoy the day. It just did not work...that can happen. At least you now know it probably is not good for her. Yes, you are right, she is happy in her world. She is not going to miss going out there...she has you and I am quite sure she is a happy, well loved pup.
As for the car trips.....one of the things that always seems to help is to hold them up by the A/C vents. I also have done that with pups that were having a bad time in the house....just took them out and started up the car and A/C. Works really well somtimes!