Pikeur Diana dressage show coat wool black blazer missing size tag 10 12 US ??

Pikeur Diana black wool blend dressage coat. I purchased this new, removed tags, and wore it to one show. I think this was marked as a size US10R, but it may be a US12 as I wear both depending on how the garment fits. Please see measurements below to help determine fit. It is in very nice preowned condition only flaws are the missing size tag and some slight sun fading on back from hanging on the trailer. Measures approximately: 17 inches from under arm to under arm across chest 24 inches from shoulder seam to edge of sleeve 16 1/2 inches from shoulder seam to shoulder seam across back 30 inches from top of collar down back to bottom edge