Thank you for reaching out to the Wefugees Community and for explaining your situation.
You gave a lot of information and I understand that all these procedures and events are very confusing for you.
Let us try to solve the confusion a bit and to bring things (how I understood them from your explanations) in an order: As you stayed in Italy many years, the German government (more specifically the BAMF) referred to the responsibility of Italy for your asylum procedure according to the so-called Dublin regulation. In the first place when you arrived, they not even examined your potential asylum reasons but only looked at the responsibilty for your application instead. They denied your application and asked you to go back to Italy. Your lawyer opened a case against this Dublin decision in court and apparently won. A reason might be your child in Germany or simply the fact that refugees face severe conditions in Italy. I don't know. However, as the court decided that your asylum procedure needs to be processed in Germany, the responsibilty went back to the BAMF. They subsequently invited you for the actual "interview" (Anhörung) - the most important part of the asylum application as the BAMF will find its decision acording to your explanations in this interview. As far as I understand, the BAMF decided that your presented reasons to have left Nigeria are not "enough" to be granted international protection or a national ban of deportation. As you are referring to another court case, I assume that your lawyer appealed against this decision as well and the ruling is still pending.
If your lawyer is asking for your passport, he might try to apply for a residence permit for you based on the fact that you are taking care of your child, which is legally residing in Germany. Please see this thread or also this link for more details on the residence permit "zur Ausübung der Personensorge". For this residence permit it will be vital that you declared the fatherhood and you share the custody of the child - not the name of the child is the important aspect here!
As your case is indeed complicated and the communication with your lawyer seems to be very low, I would highly recommend you to contact a counselling office. They offer free of charge and confidential services. I am sure they can explain you all those aspects in more detail. Please let us know if you need support in finding a respective office in your region.
I hope this helps and please don't hesitate to get back to us with any further questions.
All the best,
PS.: I saw that you opened a second thread with similar content. In order to keep a better overview and information in one place, I will close that one. I hope you understand. It would be the best if you use the comment funtion here.