I can see huge potential here for a lot of pain and suffering. This can be avoided.
Step 1: Get your feet measured on a Brannock device. Good shoe shops have them. Do this while wearing some thick socks. Record both the size and the width.
Step 2: ONLY consider boots which have the required width. No matter how nice they look, do NOT consider boots which are any narrower.
Step 3: Add one full size to the value given by the Brannock device. Your feet swell when they are working. Women are notorious for buying shoes which are too small.
Step 4: Invest in some nice thick wool/blend socks. I like darn Tough Vermont, but Thorlo are also good.