I feel for your daughter. The skin thing is such a vicious circle, since the stress about having it perpetuates it. When I was 19 I got a severe case of adult acne from stress, got so depressed, and was even fired from a restaurant job for picking. Talk about feeling LOW, the manager really liked me, but had to fire me because a customer had seen me do it and complained (cant' blame them.) ANYWAY, it really shook me up, as I was out on my own and had to work. I had been on treatments and using medicated soaps and no make up as advised, and finally, I said, screw it. Nothing is helping, I'm going to cover up with make up, look my best and pretend it's not there. It did eventually pass. :(
Anyway, as much as I sympathize and remember being a depressed teen, etc. She's 18. Tough love momma. Technically she should be moving out on her own. If she's still home as a college arrangement type thing, she still needs to be an adult, anxiety and skin issues or no.
Stating reasons why she doesn't want jobs does not classify as "can't find a job". You need to force her to work by not paying for certain things. She will be busy and socializing while at work, and even the crappiest job is temporary all that much more motivation to do well in college.
Do you have any idea what my parents would have said if I said "I might see someone I know" etc about working??!. 'Tis to LAUGH!!!! They'd be like, "Ya, and you might see someone you know out on the street when we kick you out." I grocery bagged and worked in restaurants and babysat all through high school. I had to pay for my own clothes, make up, leisure activities and car etc. (no cells in those days but BELIEVE me I would have been paying for that). It helped my depression (or gave me breaks from it) because I couldnt' mope at work or go into big negative spirals for myself like at home in my room. I also enjoyed earning money and observing all the weird co-workers and characters out in the world, but it wasn't a choice. I HAD to work. Parental law.
I would say not to let her refuse the volunteering and take away some of the comforts you are providing for her-driving, whatever you're paying for..but really, working at this age is more important. She could slack on the volunteering if she doesn't want to be there. She needs a boss. She needs money and to realize that no matter how bad you feel, you have to work. She's smart and able bodied. Be tough, mom, don't enable her to be so bored!