Why does my mom act like this?

All of a sudden, my mom wants me to be more like her. We were at the mall today and I got some new clothes, and when we were in the car going home, she was like "Why don't you dress more conservative and preppy? I WANT you to be more preppy! I want you to dress the way I did in high school." I'm in high school now (10th grade) and she wants me to wear what she wore back in like, 1985; khaki pants, polo shirts, and loafers. Uhhmm. I don't have a problem with loafers if they were high heeled ones, but I can't find any of those anywhere. And she makes it seem like I dress like a devil worshiper or something! I'll admit, most of my skirts/shorts are a little on the short side, but its not like they show my underwear or anything...and yes, I do wear a lot of heels, some even having a 5.5 inch heel, but I like them and I'll only wear them if they go with my outfit. She doesn't seem to understand that I have a style of my own...everytime we go to the mall, she wants to take me into Ralph Lauren, and Ann Taylor, and Banana Republic--places I'd never shop, and pratically begs me to get my clothes from here. What gives? Why does she act this way?