You should find more bags fairly easily.
To craft a bag, you require Rope + Leather Scraps. Rope can be made from Wool (there are some shears in Hibenheim so once you're level 10/11 you'll be guaranteed the opportunity to shear the sheep).
On top of this don't forget about Pouches - which state on them they are ingredients but really they're bags.
The patch Larian pushed out was excellent as it lets you use items inside bags, meaning you can stack bag inside bag inside bag if you wish and use the stuff directly, saves taking it out. Cleaned up my inventories of Arrows thanks to this fix.