Signs of thyroids disease.....?

What are signs of tyroids disease? I'm askin' because I'm startin' to worry a bit. Let me just start here.. before I had my son I was between 120 and 125 pnds 'n pretty active. When I gave birth I was 175, a few wks after, I was 135. Months after 140. Now, in the past yr, not even, I have went up to almost my full term pregnancy weight. I have absolutely no energy (I'm 21), I'm constantly tired, have been eatin' the same foods alllll my life, have horrible headaches every single day (tylenol nor ibprofen help), I'm moody, sometimes a lil stressed because of weight gain 'n no energy. What the heck is wrong with me????? Somebody please help. I feel helpless! It's sad when my fiance who is 6'2" weighs less than me.