Question about the thyroid medicine synthroid?

I have been going to the doctor for years with the same problem, I am always exhausted! I have tried stimulants, antidepressants and diet and excercise…The stimulant made me sick, I am depressed becuase I’m tired, and all the exercising did was make me toned! So today she was looking at my thyroid test and said I was low normal and suggest that I start taking the lowest dose thyroid medicine, daily or every other day, and see what happens in the next six weeks. What do yall think?(about the medecine…the diagnoses…. and will it do any good?)
Okay just wanted to clarify that I did have the thyroid test done, she said that there are different degrees of normal, there is high normal, low normal and just normal. I fall under the low normal catagory. I am just wondering if it is just barely below normal could that really cause the constint sleepiness, don’t have a problem with anything else, just tired.