There exists an experiment which you can do in order to find out if you’re selling yourself short, which particularly might be happening if you are a freelancer.
Here it goes: Imagine if you had to charge 10x more than what you’re charging right now, for your product, for your service, whatever it is that you’re offering?
Just doing better or working harder is not a valid answer. Think about the product/service and determine the changes you’d make. Feel free to bounce your ideas off of me by dropping me a message.