A-2 Jacket Fit Check

Hi all, sharing some pics of an A-2 jacket in a beautiful uneven brown color. Curious your thoughts on the fit - do you think it's a bit big on me? I think the body length, sleeve length and shoulder width all look good, and the chest feels about right. However I'm concerned about the stomach and waist area, which seem somewhat large. For an A-2, I'd expect a tighter fit in that area. That said, I'm likely to wear this as a fall/winter jacket, so I'll be wearing thicker clothing than the t shirt I'm wearing in the image. All opinions welcome!