How do you know you are profitable trader
By making profit
short answer.
Trading takes alot of discipline, losses, and ability to learn.
What is hindering most of us to getting to such point (being a profitable trader) is our emotion which is greed and fear
To make it big. You need greed. To cut off losses you need fear.
Both emotions help as well as they destroy
What matters is been able to manage them and be confident in your strategy.
Make plans for failure.