My girlfriend likes to wear skimpy clothes that im not comfortable with am i in the wrong?

My girlfriend and i have been going out for over a year and we had a fight regarding the clothes she wears in public. I was over and told her that i really liked the skimpy dress she was wearing. then over the phone shes telling me she wants to wear it to school. The dress is above mid thigh and im uncomfortable with it. I told her it doesnt matter if she thinks its long enough that if i have a problem with it that should be enough. Then she turns it around and says that it should be her decision and that i should care how she feels. Whos wrong here i think its her because ya she can make her own decisions but when it comes to uality i think i should have a say.