Trying to get in shape: Standard dress size for a 6' 2" girl?

I'm trying to lose a few pounds a get in shape. I'm almost 20, and I've been looking around r/loseit and some similar blogs with before/after photos. I currently weigh 170-something, and I was aiming for a low 160. But a lot of the "after" pics I've seen of other women my height are closer to 150 pounds and they look pleasantly thin, not skinny. Are my ideas of healthy weight a bit off? What would be a standard dress size, or waist measurement for a tall woman? I figure that might be a better goal that weight.

note: this may be in several subreddits, like r/tall and r/loseit, as some are relatively smaller communities.

Thanks!