Grainline Patterns - Morris Blazer - The beginning

I finally made it to the bricks and mortar shop The Village Haberdashery. I've been buying fabric online from them. They stock such beautiful things. But actually my last purchase was a few years ago... like my last post here I suppose.
I need new clothes, I am about to start a new career, and I'd like to be making and designing my own clothes. So I stocked up on some practical patterns and fabrics.
I have a mock job interview tomorrow and wanted to get cracking on a workstyle jacket. I'm not a power dresser so the casual, comfortable Morris Blazer from Grainline Studio seemed a good option.

And this wool fabric from Lady McElroy design, 86% wool and 14% polyamide.

A few days ago I started on this project

* washed the fabric

* cut the pattern pieces.
I took my bust measurement and cut the pattern to size 14.
And of course I discarded the leftover pattern edges.
Oops.
Now that I'm placing the pieces on the fabric and checking some key measurements, I note that my biceps measurement is way too big compared to the pattern piece. I need to add 2.75 inches. So either the pattern is for teeny arms or I just have giant arms (I know I have large biceps).
I looked up some good tutorials on biceps adjustment but they mostly suggest a maximum adjustment of 2" added so I don't feel I'm ready to tackle this right now as I'll have to alter the sleeve head, the armhole etc.
Disappointed.
TBC...