I'm planning on ordering a cardigan this week. According to their size chart, I would wear a petite medium, but the trench coat I bought from them is a petite small and fits fine. But since the trench is the only BP thing I own, I can't count on that size being right for sweaters.

I really need the sizing to be right because I need this for an event and might not have time for switching sizes around. Any guesses what size I should order?

FWIW, I'm a Gap regular xs or small, and a petite small most of the time. But for Loft, I'm a regular small and petite medium.