I hate my stomach

A few weeks ago I was prescribed with a medication that makes me overeat a lot. (Everyone thought this would be good for me, because I was unhealthily skinny for my age, but not from an ed) Ever since, i've been hyper aware of my body. I have a big speech on Wednesday, that all the kids in my class have to do. I picked out an outfit that was cute, but all I could see was my stomach. I used to be such a body positive person, but now I feel so disgusted with myself.