Not the best approach to work. You'll definitely not achieve perfection, but you'll spend a lot of time and effort, it's true. Try to work using time tracker for freelancers. It helps me to regulate the time of work. When I start working, I turn on the timer, and if I see that I'm sitting for several hours without a break, I understand that it's time to at least take a break. Also it solved the problem with the payment of my work. Pretty easy to calculate hours of work.