Interview Attire?

I have to pick out a new interview outfit and I'm so lost. It's just buisness casual and while I was wanting to go with just a long sleeved blouse with slacks.... the only slacks I could find above a size 8 looked like parachute pants, and the blouses fit poorly (big boob and arm problems yay). Is it weird to wear skinny jeans/linen pants for business casual? Or can I wear short sleeve? I mean it's 90°+ outside, but is that informal? But since it's hot is a blazer weird? Does a dress just make you look to thrown together? hellllllp