Problem with online check in. Help please

First, sorry for my english...

Well, I did my online checkin, but there was a little (i guess) problem.

I'm sure did everything right , but the nationality on the form left blank.
In the boarding pass, I am a citizen without nationality.

Worse: the boarding pass, despite the lack of citizenship, yet I was assigned as the European citizen (i'm brazilian)

it is possible to change this? There are fees for this change?
I may be denied boarding?

sorry for so many questions, but I'm a little worried