Hemming around curves can be tricky. Thanks to the curve, the edge has a wider circumference than the fabric you’re trying to fold it over on top of. Jessica from Running With Scisscors shares a tutorial on her blog showing how to put a narrow hem on a curved edge. Get the tute.
Have you read?
Easy Cosmetics Bag Sewing Pattern

The bag is simple, uses very little fabric (about 2/3rds of a fat quarter), has no fussy inside pockets (although you can add your own if you like), and takes me well less than 30 minutes to print the pattern, cut out and sew. But quick and simple doesn’t mean it’s not awesome!
It’s the sort of bag that is versatile enough to be used for lots of applications, not just cosmetics and toiletries. Keep all your pens and pencils in order, use it for a small first aid kit for the car, keep it in your desk at work for a few headache pills and other personal supplies.
Make some for yourself, for gifts or to sell.