Hi Cristal lyn, I am US2 in most brands, 33 bust and 25 waist. I only have one RO and is in the calf leather. I tried 38 and the sleeves and bust was very tight. Per other's suggestion I exchanged for 40 and fits perfectly in the arms and bust. Not sure if it'll stretch or not though, since I haven't had a chance to wear it much yet and it is the calf leather instead of the lamb that you are looking for.Hi there - I assume that there isn't a place around you where you can try them on? My RO size is 42. I normally wear a size 4, bust is 34 A/B and waist is 25 as well. RO jackets are cut slim in the arms, but will stretch, from what I've read. Hope this helps and I'm sure others will chime in with their suggestion(s).