Nicaragua IS in Central America just an FYI. There are localities from Central American and some of the islands off the coasts of those countries. But when somebody says "Central American" boa, it means it could be from anywhere there.
There is no way to tell what that boa is without papers and locality data. More than likely you have a mixture, which is what a lot of people have. Even the "common" Colombian boa could be a mixture of different types.
It's a good looking boa, but that's about all you'll know for certain.
I like what it's got going on whatever it is!