I'm trying to force my 18 year old daughter to not wear what she wants
Why are you forcing her to do that?
I'm concerned.
It's understandable that you want to be overprotective towards your daughter, but as long as she is not exposing any private parts or violating any dress code, I don't think you have any say about what you want to wear or not. So that she would not feel bad about her clothing choices, I would tell her too just be more mindful IPod what she wears and make sure that she's comfortable and not just follow a trend that people do.
She'll wear what I tell her to wear.
You are being too controlling here. Give her some space to experiment with her wardrobe.