Thyroid & weight problem..HELP!?

HI I was diagnosed with a under active thyroid condition last year. I have had it for 2 years. In these 2 years i have gained 80 pounds. I feel so depressed b/c this just isn’t me. I was always so skinny. I used to wear a size 5 and now i’m in a size 18. Any tricks for losing weight. I have tried alli & it just isn’t working. I always feel hungry & tired. Any help?
I am on medicine, but its just getting my tyroid under control and "back to normal" & i’m not totally depressed just down. I’m not eating b/c of that tho.