I am excited to knit The Blazer but want to be sure I understand the sizing so it fits how I want it to. My bust(a) measures 37in and so with 4-6in ease I was looking for a chest measurement of 41-43in. Looking at the chart, I assumed a size 3 would be the correct choice. But my shoulders(b) measure 18in across to the point of the shoulder and 14in to the hollow at the end of my clavicle. Please advise what size you think best. This is my first attempt at a fitted garment so I am probably overthinking it!