Try thinking of different aspects of each document, there are many different ways you can group them.
I don’t know if your teacher taught you this, but I’m taking AP World at the moment and my teacher suggests we use the acronym APPARTS. It stands for:
Author (who they are, their background, etc.)
Place/Time (and how it affects the document)
Purpose (their motives for writing, any bias they might have)
Audience (who the document was created for)
Reason (why the document was written)
Main Idea (what the document is saying)
Significance (why is it relevant?)
By analyzing each document in these ways, it should help you come up with some categories to put them into to write your DBQ. I hope this helps, good luck with your DBQ!