Welcome to healthcare magic
It is difficult to know since when you have been suffering from hypothyroidism
. But we can try.
Take a closer look in to things : sicne when do you think you started piling weight, since when do you think you started feeling sleepy or lethargic, since when did you start loosing your hair a lot.
In case your answer to all these questions is never, may be you have a subclinical hypothyroidism wherein pt does not have symptoms but has abnormal labs.
so incase you have symptoms see a doc for detailed evaluation and start treatment.
hope this is helpful.