Water Resistant Hooded Puffer Jacket

I'm so frustrated with the many other reviewers who said this ran large - some of whom said they were planning to size down as much two sizes - this jacket runs true to size. I'm just shy of 5'6" with a pear shaped body: about 150-155 lbs, a B cup, 29" waist, and wide (around 43"-44") hips/buttocks. I typically wear a small to medium top and medium to large bottom. After reading the reviews I ordered a medium (final sale - clear the rack) hoping it would be slightly oversized so I could wear sweatshirts under it. The jacket was comfortably fitted on me with just a t shirt on. The quality and construction is very decent, it's lightweight but warm, the emerald green is gorgeous, and luckily it does zip around my hips. But with a sweater underneath it's uncomfortably tight in the arms and shoulders, and when I lift my arms the whole jacket lifts up and has to be pulled back down over my hips. I may contact Rack to see if they'll make an exception and exchange for a size up. Unless there's a huge variation in sizing, in my experience this runs true to size - if not a little small.