Could Tiredness Be Due To Underactive Thyroid?

Hi, I'm a 17 year old female, I'm 5 foot 9 and 15 stone (over weight, I know) and my health has been alright, apart from appendicitis I had a few months ago. But apart from that and my migraines I suffer from, my health is fine. Recently I've been feeling really tired and have low energy. Since I've started to feel tired I have around about 17 hours sleep, even after I've woken up I want to go back to bed. I haven't the energy to do much either. And recently, I've noticed my voice changing when I'm tired. It goes sort of clear yet crackly and sounds like I'm about to break down and cry. Do you know what could be wrong with me? I thought it might be and underactive thyroid. Thank you in advance