Crop top help

Sierra • Hope you're having a good day :)
I bought a top online and noticed it was somewhat of a crop top so I bought a size up, when I received it and tried it on, it went up to my belly button. I was wondering what can I wear so it doesn't show my belly?? 
I can't have it show my belly because I'm not comfortable with that and it's for school 
I'm sorry I didn't know what group to put this is in