Old Navy sizing is an odd duck...and the sizing chart is not always accurate.
I used the sizing chart because I wanted a dark denim jacket and according to the chart it SHOULD have fit. Well, I actually went to the store and tried said item on...it fit, kinda. It was more snug than I felt comfortable wearing.
I then tried on the bleached denim jacket in the EXACT same size and if fit much more comfortably. I would see if they have your item in the B&M before purchasing it online.
Good luck!