I’ve always like letting stitch patterns determine shaping… chevrons being a particular favorite! My Tovesta bag is comfortable and a great color accent. Easy to work up, you’ll enjoying both making it and using it!
The gauge is on the loose side so the bag is lined. You could felt it instead or use a thicker yarn or just a tighter gauge (remember though it will be slightly smaller).

Finished Measurements
ca 14”/36 cm wide x 33” /84 cm long
Yarn: (5) 50g ball of Noro Kureyon #124
Extras: a piece of sturdy cotton fabric for lining approx 30”/76 cm x 76”/89 cm
Needles: US 8 / 5 mm or to obtain gauge
Gauge: 16 sts / 24 rows = 4” / 10 cm in Stock st