how to loose weight with thyroid condition?

I have always been a healthy weight. in august i was told i have hashimotos which is pretty much hypothyroidism. ive gained almost 10 lbs since i started taking levothyroxine. granted some of the weight is probably due to eating habits over the holidays and what not but usually i can bounce back. this is the heaviest ive ever been i hate and am disgusted with myself im getting really depressed and don’t even want to be seen in public. i joined the gym and have been eating as healthy but it seems like ive been gaining MORE weight. how do i loose the 10 lbs and do you think it’s from my meds?