Why I Am Physically Exhausted Without Doing Much Work?

unknown changes...I am a mother of 2. I have a 13year old & 9.5 month old. I am aware that hormonal changes occur throughout a woman's life however; I am desperately trying to find the answer to why have I been overly exhausted for the last 13years. after I had my daughter 13 years ago, I went from having boundless energy to barely being able to get out of bed. it is now 13 yrs later & I'm even more exhausted. just last week I inquired to my physican about the above normal level of exhaustion. she ordered a thyroid function test & once again it was normal. once again I am @ my wits end in trying to determine what condition I am suffering from. I don't do enough daily to be this physically exhausted. can someone please, please, please help me!!!!