I DO NOT like to take pills that a pharm cmpny has made so is there a good vit for a low thyroid.?

I have a low thyroid and it is very hard to lose weight, Dr. cann't seem to figure it out 1 says it's a little low another says your fine. BUT I am still gaining weight with only a 1000 calorie diet. And Lots of water. NO SODA! HELP!!!!!