Do you find that you have to size up when purchasing cardigans for layering? I ordered a BR long-sleeved cardi for layering in petite xs, the same size as the summer tops I had bought. Alone or over a short-sleeved t-shirt, the fit seemed OK, though the sleeves are certainly snug. However, layering over a long-sleeved button-down resulted in a lumpy, bumpy look. Does that mean I need to try the petite small size? I don't feel the outline of the top underneath should be noticable through the cardi, but I'm new to layering.