I was thinking about buy a J Crew cardigan, but I'm not sure what size to get. I usually wear mediums, but sometimes in cardigans I get smalls. For example, I always get smalls at the Gap and ON, but get their shirts/T's in medium, if that helps. I don't like loose cardigans, I guess is what that means. Do you have any advice on whether I should try a S or M? (we don't have J crew in Canada...)