>>2691647It's 23L from what I see, so you'll fit fuck all in it.
Go to secondhand stores, craigslist or any big store like Walmart and look for a hiking pack. 60-70L or more depending on how much stuff you carry around.
Ideally find an old external frame pack. They're robust, fairly easy to repair and you can strap all kinds of shit on it. You can probably find on dirt cheap.