I'm not sure that Belize allows fireworks at all. I can't remember ever seeing anyone light them off. I love the things myself, so I would have noticed.
Once, I "spent some time in a nice little office" for bringing "explosives" into Canada. I had travelled through Wyoming on my way up to Expo '86 and grabbed some fireworks there. Busted at the border, Sarah and I were subjected to a couple of hours of intense questioning. I had no idea that Canada didn't allow fireworks. Please don't let a similar situation happen to you.