Your ER doc was right, you have a lot of life to live yet and getting the right treatment to slow things down will only be helpful to you of course.
If the ER doc sent you home with meds / treatments, please follow through with those as directed.
Contact your doctor, be it a Primary Care or a Pulmonolgist if you have one. Your Primary Care can get you started on some treatments to start and then refer you to the Specialist for the lungs. Do this of course ASAP. Be honest about all from the breathlessness to the anxiety, they can help with all of it or at least get you started.
Try to relax the best you can. Anxiety and panic will cause your heart rate to zoom of course and this needing more oxygen for it's working harder. This causing you to feel even more breathless. Relax, Warm bath, good book, puzzles, quite music, whatever will work for you. You are going to be OK.
Keep us posted on when you are able to get your appointments and what type of treatment they are suggesting, we all learn from one another, thus it keeps you engage with continued support too!
Hugs to you, please try to rest the best you can, even setting up a little if that helps for now.
XOXOXOX