When not pregnant/nursing I am a 36B or 34C. When nursing is well established (and engorgement is no longer an issue) I am still 36B/C, just a little fuller. I always have one breast much larger than the other, almost a full cup size difference, whether nursing or not.
I ordered a medium initially (per the sizing guide and other reviews), but the cups were way too big. I returned them and ordered smalls, and they fit great. The small band doesn't feel much tighter than the mediums did, which I was worried about since the medium band fit well. I feel very secure in these. The cups are still slightly too big, but they definitely fit better than the mediums. Could just be me since I have a significant size difference between breasts. At any rate, this will allow comfort when I do get a little over-full during longer stretches between feedings.
They're easy to nurse in, comfortable, and sturdy. Pleased overall.
t’s really hard to judge. It’s definitly a case by case basis. I wear a XL in clothing. I’m a 38B in bras because I have a wider torso and smaller bust. I ordered the XL just because I didn’t mind if the bust was a little big, which it was. And the torso is snug but I don’t mind that either. It’s great quality and I know it’ll make breast feeding a BREEZE! The material is fantastic. If I was a C cup the XL would be perfect. But being a B it fits fine with some extra room.