Some things that work for me.
Write down what you are thinking and feeling. Putting everything into words helps you think it through and then get it out of your system. I write lots of stuff. Most of it I just delete when I am done. What I don't delete is pretty scary. I don't very often put it out there for other people to see. Just getting it out of my head helps.
You are not helpless. You're not. You have one of the most important jobs. Just being there. Holding their hand, letting them know they are not alone. What you are doing is important.
When you show up in the emergency room in the middle of the night, the docors need your help. They are very smart people, but they can't know what has happened in the past. My wifes medical history must fill up several servers. They don't have time to go through it all. My wife usualy is not able to help much.
I keep a list with me at all times. Answers to some of the questions they are going to ask. What works and what doesn't. What not to do. What drugs not to use. I've probably seen this before. They haven't. I used to rely on my memory. When you are under a lot of stress, your memory does not work very good. It's best to write down anything that might be helpful in the future and keep it with you.
Ask lots of questions. Be involved. The doctors will respect your opinion and let you share in treatment decisions if they see that you know what you are talking about.
I feel better when I stay with my wife when she is in the hospital. The last time, I slept on a cot next to her bed in the ICU for a week. I can't sleep in a waiting room, lots of people do but that's not for me. I hate those "family" rooms. I need to be there with my wife. Hotel rooms cost a lot of money. I have enough bills to worry about without paying for a room that I spent a few sleepless hours in. Ask the nurses to bring you something to sleep on, a couple blankets and a pillow. They won't kick you out.
What works for you?
I could have written this myself. You just described my life (two years) while my husband waited for his new liver. Your so right in your assessment of the waiting rooms, "family rooms", I wouldn't have described it better. Great post!