Should I be worried if I need it least 12 hours of sleep to function well?

Prevention. Not being able to sleep may indicated sleep problems that can be life shortening or life threatening. The only way to know if there are serious problems is with an overnight sleep test. I encourage you to seek help.
Need 12 hrs sleep. Yes. This is too long. There are many causes possible for this. See your doctor to determine the cause of your fatigue so you can function better with normal sleep hours.