I wear a medium top the majority of the time. I ordered a small in this, because I don't like my tops to hang off my shoulder(s). The small is perfect, still oversized, which is what I wanted. It also covers if you wanted to wear with leggings. If you want a little oversized, size down. If you want the oversized look, off the shoulder, buy your normal size.
Sweater is great quality, way lower price than a boutique. I washed on gentle cycle, and dried on low and not shrinking.