What are the side effects of taking Amitriptyline?

Hello doctor,

I am a 23-year-old, female weighing 154 pounds. I have been taking amitriptyline for six months now but it was never prescribed by a physician and now I am scared. It was suggested to me by a doctor a long time ago but my mom said no but I still remembered the name. Last year I was going through anxiety again because of a bad breakup and problems with college, at a dark point I got some 25 mg tablets and it honestly probably saved me. Over time I have tapered down to 10 mg because I have noticed significant weight gain and I am wondering if is that a side effect. I feel like I do not need it anymore and I am tired of the numb feeling but I do not know how to stop. My question I guess is does it in fact cause weight gain? Should I stop taking it? If yes what withdrawal symptoms should I expect and how should I go about it?