What is the average working hours of a freelance web developer??? I work 12hrs a day..but i think that's not enough!

On the contrary, that's sounds too much.

Even for a junior fullstack developer? @620hun

The problem with freelancing is that it makes you constantly working in your head. Because of that existential fear of not satisfing the client and not getting the money that puts the food on the table. Which forces the feeling that you have to work more. That's a very unhealthy behavior because our brain is needing it's processing time.
Do rathter work 6-8 hours and do exercise, eat healty, sleep enough instead of 12 hours shifts. Your work speed and quality will improve and ultimatly your joy to live. :)