Why am I so tired all the time?

Check your heart. I was very fatigued all through childhood and shall never forget the doctor who told my father that 'she's just lazy. Make her get up and do things.' My father took his word as gospel. I was 8 years old. I had a heart murmur which translates to mitral valve prolapse. It's when the valve doesn't close properly. Added to that I have sickle cell anemia which was discovered when I was 16, and had been on Dilantin, an anti-seizure med, since age 6. Doctors do not know everything. Go to a cardiologist and get an echo-cardiogram. That shows the heart in a 3-D video and you can see the valves clearly and if they are working properly. If it's really bad you have the option of surgery. Best of luck and I hope it all works out for you. Take your life back.