Welcome to Styleforum. Jeans stretch differently depending on the fabric. N&F jeans are also sized slightly differently, even with the same cuts. I recommend checking blueowl for accurate measurements (if they have the pair you want).
One of the best sizing tips is to size for your thighs before anything else. Waist areas can be stretched easily. In fact, you can even stretch them by hand if you need a little more size. Thighs are a bit more tricky though.