Don't get me wrong, I really like this drama. It is dark and funny at the same time. I like that her life sucks more than mine. But this whole is she or isn't she going to die thing is killing me! I know it is part of the story, but I hate the suspense! So what do y'all think? Is she really gonna die in the end or is this just a plot device?

Nah, I think it was clearly suggested there's another person in the 4th bed when they were in a hospital. Was she really sick, she would get a check-up already and it would be stated for the show to make her more depressed. And a doctor would probably say something to a potentially dying person, not flirt with her.
She can have a stress related symptoms.
It is a plot device, but a good one. She's reaching important realisations as if she was to die. It gives her an extra spur.
Good point. Thank you! I tried venting to my sister. But she doesn't really watch Korean dramas so her response was, you're right, what if they are pulling a John Green and making it seem obvious and then boom she dies. Not very reassuring. 
I agree - plot device probably. Feels more like a "learn how to live AS IF every day was your last" kind of story rather that a "living life knowing every day might be your last" story. Also I think the point made by namopanik that if it was real the show would confirm it 100% and then milk it way more is probably true. So I'm like probability 90% not-sick, 10% sick. (if she is sick then that doctor is like etically waaaaay out of line)
I didn't realize there was a 4th person in the bed... namopik also made the good point about the doctor showing no concern at all for her health the multiple times he has met her. I understand he's an opportunist (turning their story into a book) but I can't think of any doctor or anyone so bad they wouldn't try to encourage a terminal patient to seek treatment.