Prom dress advice for me?

Hello. I am going to be going to prom in the spring time, but need help with a dress. I'm not a thin, slender, girl, I'm more of a hefty girl with some meat on her bones. (I weigh about 155 if that helps.) I was wondering if I could get a dress that would cover up my "belly" but still look good and sort of sleek? I don't have a big belly, if that helps, lol, , but like I said, I eat good. Just wondering if anyone else has dealt with this too. Also, what size of dress do you think I would wear? I don't wear dresses at all, so I'm kinda lost! Thank you so much!