Really nice looking bag. I love how you designed it "by the seat of your pants". I do this quite often when making custom things for the family.
I have made bags for fishing, laptops, iPads, jumper cables, PlayStation console all without a pattern to start with. My husband's work vests are made freehand. So are his work aprons since a lot of customization has to be done on each one. He has one for woodwork and everyday usage and one for metalworking.