Background
I met this girl, who we'll call Alice, about two years ago, and we have been casually dating for the past 2-ish months. She has been an off-and-on smoker for a handful of years, and when we first met, it was during an 'off' period.
However, Alice picked up the habit again about 6 months ago.
When we first started casually dating it didn't bother me much, but it's progressively become something I don't enjoy being exposed to. I also have found that I'm not comfortable dating a smoker in general, due to their associated health risks and the expenses of such a habit.
Alice was originally going to stop smoking last month, and made great strides to cut down how many cigarettes she was consuming daily. However, she did not fully stop by her target date. She has continued to still smoke a couple times a day, and I can always smell it on her when we see each other.
What I Have Tried
I told Alice that this bothers me, and I can't see myself in a long term relationship with someone who smokes (emphasizing that I'd be very concerned about her health). I also expressed to her that if there's anything I can do to assist her, to let me know. She was understanding, expressed that she did still want to quit but that her biggest vice was during her breaks at work, and said she would make a bolder attempt to completely cut it out of her life.
That being said, a few weeks have passed and I feel like things have actually gotten worse. Instead of only smelling the smoke on her on her work days, I've noticed I've also smelled it on her on two occasions where she didn't even have work that day.
When I asked her about those specific days, she gave me very specific reasons why she had smoked on those days:
"I had a lot of anxiety about going to the doctor."
and
"That was just a habitual smoke while I was driving around."
I've found it hard to figure out where to go from here (and am in need of help) because:
Alice has a diagnosed anxiety disorder that can make communicating difficult.
If I don't approach the subject delicately, it's easy for Alice to shut down. I want to make sure I don't make Alice's smoking habits worse by sounding like I am demanding or attacking her.
I feel like this has also made Alice feel like she can't talk to me about her progress, because she knows it can potentially bother me (and the idea of possible tension would make her very anxious).
I know that I don't understand what it's like to quit smoking.
My most primitive feelings are that Alice doesn't want to quit smoking, or she would have done it by now. However, I know that breaking this addiction can be difficult, and I can't understand what it's like from her point of view. If Alice is telling me that she does want to quit smoking, I don't feel it's fair for me to "tell" her otherwise.
Question
How can I express my feelings about Alice's (seeming lack of) progress to her in a supportive way that doesn't downplay how much this situation worries/bothers me?