Upvote:3
It is unlikely, that a reentry ban has been imposed on you, but to make sure, you have the right to apply for a release of information from the German Central Register of Aliens. The application is free of charge, but you need a notarized confirmation of your signature.
Obtaining a residence permit as a father of a German child should be a formality. At least as a Brazilian citizen, you can even apply in Germany during a visit as a visa-free tourist.
For further questions regarding residence permits or taxation issues, you should ask on the Expatriates site, as it is off topic on this forum.