I had to have a huge talk a year or two ago with one of my longtime friends as he never understood acne. Even after a solid lecture he still asked "why don't you get a cream or something?" He finally figured it out, at long last, and knows to shut up now. I was at least lucky enough that he was the only person to really give me trouble about my skin, and even then not in a bad way, just the classic "Dude you have a pimple there" as if I didn't notice.
I'm 19 too! From the other coast though, and a bit further north haha.
I think it's great that you're still socializing and being active and stuff, regardless of your skin. When my acne was at it's worst I pretty much shut down and I regret it every day. I'm also in the boat now where I have to watch every single thing I eat to maintain clear skin. I haven't had pop, chips, pizza, chocolate, or anything like that for nearly two years now. It really sucks, sadly all I can do is stay disciplined.
Take her out. For sure, take her out. Maybe things will work, maybe they won't for whatever reason, but for your own good please don't back out and leave yourself wondering what if. I did that too many times, and it messes with your head way more than any rejection will.
As far as talking to her, do what the others have said and try to find some common ground between you two so that you have somewhere to start. I hate groups of people, but I'm a pretty good one on one conversationalist and it's a very powerful tool.
Haha there's so much to say when it comes to this topic, but it's best to keep it simple. Just try your best to have a good back and forth conversation, and go from there.
Acne aside, can I ask why you are so concerned about 'where you stand'?
For me, I try to keep clean shaven/well groomed, and wear decent clothes that fit. That and posture, posture is very important. My opinion would be that if you ask 10 different people to 'rate' you, and they gave you honest answers, you would get 10 different answers. It doesn't mean you're doing anything wrong (or right, for that matter). It just shows that it's not worth worrying about what others think. You can't please everybody.